OK, I flew 4 more flights this afternoon. Flys solid as a rock.

On a hunch I checked lateral balance, and sure enough, the plane was heavy on the right. I put some wood screws into the end of the wing on the left to balance it out, made a couple of very small adjustments on the neutral position on the ailerons, and took it back out to the field. Made all the difference in the world. I also put some expo in to smooth out the controls a bit at center. Flew one 5 minute flight to finish trimming it out, landed, checked all the fasteners again, torqued the muffler, glow plug, head bolts, engine mount, etc, filled it back up and started to have some fun.

Flew 3 more 10-12 minute flights and it's a joy. By the last flight I was doing split S's, Immelmans, inside and outside loops, slow rolls, snap rolls, stall turns, spins, you name it. Not real pretty, mind you, but the basic maneuvers for sure. Even tried some inverted flight up high....very smooth and doesn't require near as much down elevator to hold it level.

The engine still isn't totally broken in and I've still got it pretty rich, so I can't really judge speed or power at this point. I'm currently running an MAS 14X8. The battery on my tach was dead so I haven't checked rpm yet. Don't really have a handle on what kind of vertical it's going to have, since the engine isn't peaked yet.

Any suggestions on props for the OS 75 that might be more appropriate?

Picked up some trim material and will be adding stripes to the bottom of the wing and stab in the next day or so.