Does anyone have good cam specs for propane? I know that each engine will be a little different. I have a 351M. But I am looking for good specs. I am planning on rebuilding the engine with 10.5:1 to 11:1 compression. The 335 engine forum likes the Comp Cam 255 for RV/Towing application, so that is where I intend to start, but I think I have to increase overlap to keep the exhaust valves from overheating. Can this be done without sacrificing dynamic compression ratio?