89 350 in a silverado

I'm sorry if there has already been a thread on this, I did look though. I bought an 89 Silverado with a 350 TBI, (for a song...almost literally).
What generation would this engine be?
I've heard that, at some point, GM changed the flow pattern making heads/intakes incompatible with some blocks.
I want to build the engine: IE Built proof bottom end, 400 ish HP, with a 4brl.
Thanks!

Probably late 80's through the 90's. Get the #s off the block and we can go from there.

You have a revised Gen I block which means it has a 1 piece crank seal and a few other mods like hydraulic roller cam/provisions.

Gen II is the LT-1 with reverse cooling

Gen III is the the LS based engines.

thats what I needed to know! thanks... :3dSMILE: