I have a 87 firebird with a carbureted 305 thats junk. i want to swap out for a 350. Can i use any carbureted 350's?
Can i use 350 throttle body and switch intake manifold and carbureter?
Do i need to look for 3rd gen specific motors?

 

You haven't received any replies because all of this has been answered a thousand times. Really. Short, half-hearted response: Go find any '87-up 350. Turn the flexplate or flywheel by hand. 2 full turns. No clunks? Good, pull the intake manifold. Any visible cracks in the lifter valley? No? Good, pull the heads. Check top of bores for ring ridges, about 1/4" down. None? Good, check the bores for visible cross-hatch pattern remaining from previous honing. Some? Good. Back to the heads: Casting number end in 062 or 906? Yes? Check for visible cracking between the center 2 combustion chambers on each head. None? Good, buy the whole engine. Any other casting number on the heads? Toss them. Get your 081 heads off your 305, get them rebuilt at a local automotive machine shop. Better yet, have them cut for larger 1.94" intake valves, but only if they can add a 75 degree throat cut below the 60 degree cut. Otherwise the larger valves will slightly hurt instead of dramatically help. Now, whichever way you went with heads, get some stainless 1-piece swirl-polished undercut valves. CP has them for $ 80 per set of 16. Have your local shop put a 30-degree back-cut on all of them. If using 081s, have this done before they cut the intake seats. From your 305 save the roller lifters, the spider, the dog-bones, the pushrods and rockers, the cam thrust plate and screws, and the spider screws. Also the oil pan, rear main seal carrier, and valve covers. When you get that far, let us know.