[niterydr]

The cas sensors are completely different between the years, they don't interchange very well and deffently don't play nice together, the only thing worse is 95-96 heads in 99 cars (aka ricky's). The cams are different, I actually think the cams might not be swapable between nt and turbo, I don't remember. I am sure there are many other differences like oil passages.
Also on 7 bolt motors, the headstud/bolt diameter is actually different, so 7 bolt heads have to be drilled over 1mm to interchange with 6 bolts (or is the other way around, im tired, sorry).
I think the cas pickups with the different 1g sensors are interchangeable, in that case i'd suggest putting the 90 cas in.
Also I think the valvetrain might be different, I really don't remember, and am to lazy to try to remember/research this more, maybe tommorrow.