I own an 1985 IROC, I wanted to install a 350 and use the TPI setup. Will I need to change the computer? or will the MAF compensate for the added displacement? What other parts will I need? Also here is the 350 I was interested in let me know if you all have had a good experience with this crate engine. Thanks to all who answer.

http://www.jegs.com/p/GM+Performance...10002/-1/10763

 

That engine has very poor heads. There is also a 290 HP version for a little more money, but still has the poor heads.

Your TPI would bolt to it and generally run fine. A 350 knock sensor and module would be helpful. The '85 TPI ECM wasn't their best effort, if you could find an '86-'88 version, preferably an '87-'88 L98 unit, that would be a step up.

Your current 305 heads are better than what comes on those crates. Buying a shortblock and fixing up your 305 heads (1.94" intake valves, basic port and bowl clean-up) would give it a lot more power.

For reference, that "260 HP" is "gross" flywheel HP. Your LB9 was rated at 215 HP, which is "net" flywheel HP. Your LB9 would put out around 250 "gross" flywheel HP - if you consider $1800 plus installation for a 10 HP increase a good investment, we need to talk.