This is just a small suggestion, but if I were you I would put the smallest cam in your engine that you can find due to you running propane. I built a stroked 350 which of course is a 383cu.incher for my 86 4x4 5 years ago. I have been using propane for almost 30 years now so I have tried a lot of combinations. I know my engine is a V8 but it pulls like an ox at low speed and highway speed, My gear ratio is 3.08 with a 4spd manual transmission.
I wanted the cam to have the shortest duration with the highest lift, because I wanted to cram as much fuel and air in there at low speeds as possible and I also wanted an early closing exhaust valve. No more than 34* of in. and ex. valve overlap. This will also give you a nice smooth idle. With a 6 cyl. I would go less.My cam has a 111* lobe separation angle and is a dual pattern. I have excellent torque and power from idle to 4000rpm but I very rarly take it past 3500. Good flowing intake,heads and exhaust also make a difference. Fuel mixture screw does not have to be any more than 1/2 way out. My compression is in the nieghborhood of 10 to 1 but with a small cam like this your Dynamic compression will most likely be higher than would be practical if you were using gasoline due to the higher octane rating of propane. Detonation has never been a problem. Mileage with propane will always be less than gas since it does not have as many BTUs as gas but I justify this because it is 1/2 the price.
The cam is the heart of your engine. With a full size truck and a 6 cylinder engine on propane, bigger is definately not better when it comes to the cam. "RV" cams are to vague. You really have to look at the numbers. Good luck.
Brian
