Hi Frank, I am not an expert. I am barely a novice at this.. Carbking is the expert, and hopefully, he will chime in. He has recommended Zenith + Stromberg updrafts as replacements for Marvels. He also recommends getting one that was designed for as close an engine to yours (cu. inch) as possible. Although mine was designed for a 248 and my engine is a 257, it is pretty close. Plus, a slight variation of this carb (venture size?) was made for a 41, 42, 43 GMC Truck with a 257. You will have to make or buy an adapter, since the Marvel flange is offset 45 degrees.