My Rev 3 Turbo engine rebuild...please chime in

Anything to open up the exhaust downstream of the turbine helps with efficiency of the CT20B as they tend to run out of puff from about 5500RPM. I suspect they are a bit too restrictive in their turbine housing.
CT20B has a ceramic turbine wheel which can relocate itself to the muffler!! Ruins it's efficiency.
If using standard cams and valves then you can be pretty confident by renewing just the valve springs and stem seals. But if bigger lift or duration cams or over size (therefore heavier)valves are being installed it would be advisable to use stronger valve springs. Preferably duel springs for better valve control without being overly heavy in tension and causing excessive load on the whole valve train.
Are you assembling all this yourself ?
If not I would strongly advise that you spend the time to at least double check the valve clearances before the head goes onto the block. It can be a painful, slow, annoying job to get the clearances spot on correct but they need to be very accurate. Preferably toward the looser end of the spec.
I've seen several total catastrophic engine failures that I suspect were caused by incorrectly assembled valve train components by supposedly competent workshops ??
Slightly different area but have seen workshops make a mistake through lack of time or knowledge of these particular engines. Behind the lever carrying the cam belt tensioner pulley there is a special thick spacer washer which can easily be forgotten on reassembly. It should be included in the new pully/lever assembly from Toyota.
Hydraulic tensioner should be renewed also. Old one can be reused if in good condition but not advisable.
When compressing the chromed rod into the tensioner cylinder it must be moved very, very slowly using a large vise.
Particularly make sure all the parts are for Gen 3. Belt, tensioner, pulley assembly, water pump needs to have a cast type impellor. Genuine Aisin/ Toyota. (Not a rubbish pressed steel impellor that will just thrash rather than pump).
Pay attention to the fit of the gasket between block and oil pump. (There can be a mix up of part numbers).
Hope this gives some insight for thought.

Thanks for the replies guys.
I'm going to print out Falcon's advice as well as a "do it in this order" list from Pete Drury and give it to the engine guy when it gets booked in.
I'm going to fit a dump pipe sourced from England and a Legalis Type R system with special "No 5" rolled exhaust tips which cost me heaps LOL.
I hate the slash-cut look and although the rolled tips are available here they would have to be TIG welded on and it would cost about the same so I'm having it done by Fujitsubo in Japan prior to shipping.
That oughta make it breathe better especially with the new cone filter and Apexi Power Induction Kit I had fitted in Japan prior to moving back here.

This is the tip I'm having added to the Legalis R
( for those who don't read Katakana it says: "roundo sturaighto" /round straight