Need your help with my engine, not sure exactly what I have. I bought this 71 GTO convertible last year, I finally have got around to working on it and in the process if tearing into the engine. so this is what I have found. the block is a 1970 400ci engine with the #9799914 on the rear of the block. #'s around the distributer are 70, and L109. the heads are 7H1. Engine has Hooker headers. The carb is and Edelbrock 600, and sits on an Eldenbrock performer intake. It's been converted to the serpentine belt out front and electric fan. I know nothing about what all this is together. Here are my questions. Why would someone put 350 heads on this engine? Is this a Ram Air iii block? Is this engine something that would need to run hi octane fuel. I bought this car for a driver, so not to concerned about non matching numbers. Thanks for your feedback.