Well I better get this block and work out the water passages then, buying a 3S head gasket will at least let me choose a thickness for compression ratio.
I think I'll get the car running first before I look at swapping ECU's. We'll see how it goes and try from there, I scored it with a GT4 purchase years ago. 
This is good, helping me make some decisions haha. So ATS or CP pistons? and Carrillo or Pauter rods? I can order the end of this next week.

Cp pistons and which ever of those are cheapest, both are quality.

If you could list which parts you already have (obviously all head components) and which parts you still need to order (still need to order the fueling gear etc?) it'd help with us giving you advice.
 
There are pros and cons to any way you go with the crankshaft and it all depends on what you intend on doing.  Running 5S big end sizes gives you are a larger bearing surface and also more overlap on the big end and main journals (ie, stronger) however you end up with increased bearing speed.  Whether or not this is a problem is arguable and will depend on the intend RPM usage and oil quality amongst other things.  A benefit of the 3S journal size (at least when I looked) was better bearing selection.  You only got access to budget/basic bearing materials in 5SFE sizing (ie, no ACL race spec, high spec clevite etc)  This may have changed however in the last year or so, not sure.
 
I like the billet brian crower crank for a number of reasons
a) its 4340 chromoly, ie, stronger then the alloy used in the standard forged crankshaft
b) the flywheel PCD is 3SGTE, no butchering flywheels to suit 5SFE crankshaft
c) the flywheel bolt holes are M12 vs M10 of the 5SFE bolts.  Means your using stronger bolts (and can use the ARP 3SGTE bolts).  Whether or not this is a weakness is also arguable.  I haven't heard of any flywheels seperating themselves whilst using 5SFE bolts, though, its not something I'd leave to chance.
 
Regarding pistons, I highly recommend the CP pistons.  They work fine with 1mm OS valves.  Pauter and Carillo rods are much more expensive then Eagles and I suspect that Eagles would work fine for your application.  Your not looking at >700hp.  They are also lighter then either of the other two listed.  I am using custom Carillo rods but for a number of reasons that do not apply to you.
 
Your going a little marginal on your pump.  I'd probably look at something a bit bigger, maybe the walbro 400lph pump and some 1000cc injectors.  Fuel is not something you want to be running lean on.  Get a standard gen 3 gasket (or aftermarket for gen 3) and machine the block to suit, imho this would be the best option.
 
Regarding headstuds, standard ARP's would probably be fine for you, unless your looking at pushing over 30psi of boost.  If those, I'd suggest you bypass the L19 studs and go straight to the custom age 625 studs.  L19 have some downsides in the way of hydrogen embrittlement problems.  Okay for race teams that replace them all the time, not so great for regular joe.  Regarding the crankshaft bearings, if you are grinding to 3S size then just get the standard 3S size bearing and have the crankshaft machinist grind to whatever bearing clearance you want.  Get 0.25 over on the main journals and have crankshaft ground for correct clearance.
 
To make the most from your setup you'll likely also want to upgrade from the greddy side mount cooler.

Thanks for all this advice everyone, it's good to be put on the right path.
Totenkopf, do you still have your billet cranks available? I'll check out the prices with Crower.
Regarding the pump and injectors, do you think it would be fine for me to get the car running with what I have and then upgrade and go for another tune? I think that's my best bet for now, but I agree with you.
Yeah I have the head gear and the fuel gear I have listed above, basically need to order my bottom end parts. I'll hold out on the HG until I have the black assembled so I can choose a compression ratio properly unless U can find out the volume of the CP pistons. 

if you already have the walbro and 750cc injs then yes they will still provide enough for minimum 350rwhp.
 
mate of mine in his gt4 (gen3 motor, cams etc) has the gtx3071 and sard 800's pushing 285awkw/390hp approx.
 
how much power are you aiming for? do you already have the turbo?

I think I'd like to aim for similar to start off with, and once I get it running I'll upgrade parts.
I have everything I've listed in the first post except Pistons, Conrods, Bearings, Head Gasket, Turbo manifold, head studs. I'll go out to the shed now and have a play.

Unless the billet crank works out to be sub $1000, I wouldn't go that route given your plans. 5S & 3S cranks have been doing the hard yards for years without dramas.
 
With that GT3076 turbo, you won't need more than 8000rpm, in which case Eagle rods will hold up fine with the added benefit of reduced weight. If you do however, intend to go beyond that turbo & rpm limit, good idea to invest in Pauter/Carillo rods.
 
Another suggestion I'd make is to use a 3S crank for the better rod ratio. You'll still get increased displacement due to the larger 5S bore (along the lines of approx a 2.1L motor). Less hassle with crank gear & flywheel bolts too. I had a 3S block with 5S crank (not so far apart in displacement) & my GT3037 spooled exceptionally well. The better rod ratio should make for even better setup. In conjunction with the lighter Eagle rods, it'd be a nicely setup & priced motor. Btw, I really like my CP pistons 
 
I'd expect such a setup to hit 20+ psi at around 4400rpm. The below is with a restrictive exhaust/cat, but slightly smaller hotside GT3037/76.
 

 
Would leave you with a wide 3600rpm of serious fun to play with.

The off the shelf pistons wouldn't work with the 3s crank would they?
Wouldn't you need taller pistons or longer rods? 

if you used std 3s crank then you'd use the std non stroker 3sgte pistons, you'd just need to get them in an 87-87.5mm bore for the 5s block

or you could use the 5sgte pistons and get longer rods made which is sort off what i've done, except i have to get custom pistons anyway due to beams head not suiting gen1-3/4 3sgte pistons