What Is The Problem Here ??????
Rcign. .Bme, DA, 3W and others have a REPUTATION. . usually good. . call it a 5 star rating .. .
I'm sure YOU do as well. . . Even given that high "rating" though, 3W still has problems with their motors (I'd give them 2.5 stars) BME has weedie conversions at this time and is upgrading to proprietary parts only (4 stars) DA is overrated for what you get but has great customer service (4 stars) ZDZ has ignition problems STILL (3.5 stars) and Zenoah is a dumb, simple, overpriced, but reliable powerplant (3-3.5 stars)
Where does the independent "conversion" supplier fit in? It depends on their reputation .. A&H is probably a NEGATIVE 5 stars ( I can't imagine a worse built motor with a poorer support).
You can sell conversions all day long. . . IF you can sell YOURSELF.