The head will bolt on and you'll need the intake manifold also cause the GE head has TVIS and intake ports are different.
FYI all 3S and 5S heads are inter-changable. Just don't know if the cams got same grind or not. Of cause the GE will have different cam then the FEs.
I haven't heard anything about having to get adjustable cam gears but you might have to. The 5s block is a bolt on to the pre 92 blocks so most of the 5th gen celicas. The last year of the 5th gen celica 5s block doesn't work since that is a 93. And none of the 6th gen blocks work unless you get some machine work done.