Gen2 throttle bodies fitting is different, and i think they are 2-piece casting when gen1 is 4-piece. You could take gen2 head and throttle bodies and put them on gen1 engine, but you need throttle cables, they are different length, on other side. There is also idle adjusting motor and 8 injectors on gen2 throttle bodies, and for that you need gen2 ecu, wiring harness, magneto, camshaft position sensor and offset pin for intake camshaft. I would take the gen2 cams, install offset pin, take out cam gear, switch roller bearing other way around, it differs, install adjustable gears and get few hp whats there. Easiest is to put some hipo parts in what fits straight on.