If you understand how these systems work, it would be cheaper to make your own. If you don't, (and I didn't at the time,) I'd recommend the Powershot2000 system. (I see that you've got a BullyDog chip, and that company also makes a propane system, but I think it's got it's weaknesses when compared to a Powershot2000.) The Powershot is simple, relatively foolproof, and will give you a definite boost in power, approximately 80-100rwhp.
With your list of mods, you've got all the stuff you need to maximize the system, but you'd probably need to get the chip reprogrammed for propane use. With propane, you don't want/need any fuel timing advance, and your chip most likely has that, as a means to boost your current power.
Since BullyDog sells a propane system of their own, I'm certain they can reprogram it for you with a more suitable program.