RE: Engine for my 73” CAP
I'm flying an older Hangar 9 Matt Chapman CAP 232 with a Saito 150, and it seems to be powered very well. It comes in at around 14 lbs or so, and the 150 will take it vertical for quite a while before running out of steam, and will probablly hover it with a flatter prop. (I'm running a 16x8, I like 'em fast).
You might want to also consider a Super Tigre 2300, at $150 they're hard to beat and it swings an 18" prop.
Andy