I going to build up a 454 on propane and want to get the most performance for the least amount of money (yeah yeah you';ve heard that before). I know very little about propane but have been doing a ton of research and know a general idea of what I want but not what specific parts I need.

I know I want a different cam that has a longer exhaust side but which is a good one to buy?

I'm planning on using the msd adjustable timing control, but other than those two things I'm at a loss as to what to use for everything else.

And also I hear good things about the ohg x450 mixer, is this a good one to use? pros/cons?

For starters compression and/or cam that provides good cylinder press.....keeping cylinder pressures high. Propane has high "octane" but has lower BTU's vs. gasoline.....you'll want compression/high cylinder pressures to recoup some of the loss in energy.

what he said.

how much compression, 9:1 , 10:1???

If I was doing it, I'd go 11 or 12:1. And select a typical performance cam (meaning:choose the cam like you would for your gasser. You won't be picking a stock grind, but you have an idea of how radical you want to go, use that as a guide).

Alex.

Just remember a milder duration cam may increase cyl press. beyond even the limits of the propanes octane. In other words if you built a static comp ratio motor with 12:1 and a real mild low duration cam you may still end up with too much cylinder press. (Static vs. Dynamic compression) for the octane. Search and learn about "dynamic compression ratio", it will give you truer and more accurate results.. You'll need a lot of information regarding your build plans to pick the right cam. Talk to some cam grinders about your application.....Crane, CompCams, and etc.