I have a 305 in my 90 IROC and the motor is tired, I would like to keep this swap simple. The L98 came factory in the car so it makes sense to me to swap to that motor. What I need to know is what I will need to complete the swap, besides the motor, like sensors, computer, and what ever else I'm missing. Any help would be greatly appreciated!!!!!!!

Ever think about just swapping in a ZZ4 instead? Will make much better power and bolts right in.

I wish it were that simple!!!! I live in California, and we have really lame smog laws that prevent me from doing that!!!! What I really want to know is about all the little things that need to be changed like the knock sensor, if I have to change the whole computer or can I just change the chip, and whatever else I am not aware of. Also the ZZ4 does not have provisions for an egr on the cyl heads, heince it wont pass smog. Thanks anyway

The '86-1/2 & up Vette L98 had the same heads.

Put in the ZZ4, equip it like a Vette, you'll pass. You'll have to go through the "motor change" process, but if you're good with that, you'll be good to go.

You could always get the ZZ4 shortblock and put some heads on that have the crossover passages - that way you can keep the EGR all nice and legal-like. Plus, you're not buying an intake and distributor you don't need.

Sorta like in the sig.