Hey in need of some advice, pretty new at this so bare with me. 
Bought a 1996 sw20 na 3sge mr2 wanting to swap with a v6 camry engine.
really just wanting some advice.
first what type of engine is best compatible with the car, ive read that the 1MZ-FE  engine is a good way to go,
can i use the 3sge transmission with an adaptor or nah 
do i need a new ecu with the wiring harness? 
and is there anything else i need to look out for 
cheers in advance.

1MZ should be fine. S54 gearbox is often used in V6 swaps overseas. UK etc. Won't need adaptor.
Driven half sensibly it should survive. More at risk if its an open diff type. They don't like spinning up one wheel.
Main complaint is the lower overall gearing in 4th and 5th. Especially 5th highway cruising.
Yes, need 1MZ ECU. 1996 radiator will likely need it's tanks opened and the tubes rodded out. Will probably be adequate for the job so long as it is properly sealed to pass all the air through it as originally designed.
Does your 1996 car have A/C ?

Yeah it has an ac and im pretty certain its an open dif. mainly just trying to make it my daily with a bit of hp so aint going to go too crazy with it. 
so the s54 gearbox has the same bolt layout for the 1mz? and basically just use 1mz wiring harness and ECU and should pretty well be plug and play? 
would the 1mz fit the og engine mounts or am i dreaming lmao. 
and does the year model of the engine matter too much or can i use basically any 1mzfe? 
can probably find someone to help with the radiator 
thanks in advance bro. 

Having A/C and being a 1996 and I assume Australian Delivered car it should have the larger radiator and two fans.
So if radiator is in completely sound good condition on outside then all it should need is to be properly cleaned inside as I have previously suggested. Same story with steel pipes under car. V6 will generate significantly more heat so whole cooling system needs to work well.
1996 is likely an open diff but not absolutely. Some were factory delivered with a torsen and they behave differently to a plate type LSD. Gearbox should pretty much bolt straight up I think.
Timing case engine mount can be sourced from Paul Woods in UK. He is the bloke who knows it all backwards.
 He can better advise you regards wiring looms, ECU. etc.
Don't forget to budget for a properly thought out exhaust for the V6. Pure heaven when it's done correctly.
Where are you based ? Often times someone on here will have the bits you need and can even be willing to help.

How would i get in contact with paul woods? Im up around Queensland Goldcoast/Brisbane area. if someones happy to help ill shout them a carton of beer. The exhaust would have to be custom made other than the exhaust manifold because of the location of the engine? should be able to sort the radiator out

Google Woodsport. UK. MR2. Hop on the English MR2 forum.
You may discover the exhaust manifolds are not entirely satisfactory as I think one discharges too near clutch slave cylinder etc. I don't actually know as I've not done this swap myself.
I've heard talk of swapping exhaust manifolds side to side but I kinda doubt that is very likely.
To achieve close to equal length of front and rear bank pipes to a decently flowing merge within available space and get over the rear crossmember will cost money.
Catalytic converter, muffler, 180 bends under boot floor. Very nice when done properly and will sound glorious.
Can be a nightmare if done half arsed. Too close to oil sump or clutch stuff. Not clear of anti roll bar or crossmember.
I have exhaust headers to merge to over crossmember here if you want to have a look. 2GR. V6.
Brisbane bayside. Redlands area.

Yeah if you have a header i could use would be appreciated, would you recommend anywhere that might be selling a decent 1mz with everything included from ecu etc like jap imports? real keen to get this done now haha

Joelcog
Yeah if you have a header i could use would be appreciated, would you recommend anywhere that might be selling a decent 1mz with everything included from ecu etc like jap imports? real keen to get this done now haha

the 1mz is a common Australian sold engine, 1997 to 2000 something or other in Camrys. Buy one of those, it'll have most of what you'll need.
 

and Paul Woods has a profile on this forum, could try and PM him and he might respond.
 

PM Sent.