Oh yeah, I did briefly mention the 3sge beams pistons, however 3sgte, 1jzgte, 2jzgte, and certain 4g63 pistons with 22mm gudgeon pins (I think 22mm is the size...) will all fit and give a nice low compression ratio. Of course custom forged are available too!
The nissan SR20 exhaust manifold is obviously topmounted with a homemade adapter out of 12mm plate steel. An aftermarket topmount SR20 manifold would be able to be fitted without the adapter as the front and rear bolts line up and the rest are a simple file job in between the SR mount holes for correct fitment. The 3tc port spacing is identical to SR20.
I'll add anything else if I think of it...
Cheers,
Jason