Just bought a 1941 Pontiac Streamliner project car. It was bought without an engine or trans. It already has a 74 Nova front clip installed. The two possible engine choices are either a 302 GMC, or a Pontiac OHC Six, out of a 1969 Firebird. I'd be using a T-5 5 speed for a trans, with either engine. The GMC is a NOS short block that is still in the shipping crate. A used big port head goes with the 302. I already have a complete small port 270 GMC out of a 56 grain truck, and a Nicson 2x1 intake for a 302. Do not have any headers. The Pontiac engine was swapped out of a 69 Firebird, (for a 455), about 30 years ago and has been stored since then. Supposedly, it ran well when it was pulled, and was well oiled up to preserve it. It had a 3 speed behind it, but the trans is gone. I don't have any experience with the OHC engines, but have worked on several GMC / 235 Chevy sixes. So.....How do these compare? What are the advantages / disadvantages to each one? I'd like to keep the 41 all Pontiac, but also like the idea of a GMC Six in it. After a quick look around the internet, it looks like parts are easier to get for the GMC??? However, the pan clearance on the GMC is a question mark.