I would go for both heads off of the same vehicle. Even if it's the same cam as the monty, there will be a different ammount of wear. That situation will give the possibility of an unbalanced fuel/air distribution & poor running. I would also not use the other cam from the caravan in your head, as machining tolerances may be too tight ow just sloppy.

Ed

Yankneck = Yankee ingenuity with Redneck stupidity.
"How can I break it better?"
89 Raider 3.0 w/ 31's for now