RE: OS 91 VRDF experts wanted
The .91 VRDF I have was a deal too good to pass up several years ago. It's no Nelson, Jett, or OPS but still a fairly high performance engine and should work well propped properly.
What is going to be the interesting part of the project is to fit an airframe to this engine. I'd like to keep the wing loading in the 12 oz/ft range, that's probably going to be the main design criteria.