Hi Chad, I have a 7AC conv. with the Buzz Wagner 0-200 STC, I like it I think it makes a good conversion, a couple of advantages of the C-90 conversion is the C-90 swings a longer prop and the wing spar AD is a one time (provided no wing damage like a ground loop) insp. and with the 100 hp 0-200 its and annual requirement, down side of the C-90 engine is finding one and they are not cheap, where as 0-200 are easy to find. If you have any questions I'd be happy to try and answer then for you.