I ended up with a Brodak Oriental kit - sort of a shaggy dog story - and on a whim built it.
Used a OS .35S on uniflow for 2-4. Came out way nose heavy even sans-muffler. I'd say if you build one use a 1/2 shaft extension and move the motor back. A friend I fly with did that to his, used a Fox and it seemed to work better. I had to add two 50 cal round balls to the tail to get mine to fly a decent square.
The plans show no rudder offset. Not good. Both of us who fly one have struggled with line tension issues and none of the myriad of trimming permutations have really fixed it. The only thing that seems to help is to fly it fast. I'm flying 60' from handle to spinner. Just over 5 seconds. I'm old-school and like to fly on the slow side.
The most successful thing I've done is to add the "Ward board" to the nose, copying John Ward's mod. That really helped stability in square corners.
It is THE most un-tolerant of wind or turbulence design I have ever flown. A little breeze is nice, but if it's dead calm it will sometime hit it's own turbulence on eights and waggle its wings, and you better be ready for it. I suspect that's because of the long, un-tapered wings.
If you build one cut the rudder vertically at the end of the fuse and add about 3/8" offset. Better yet make it adjustable since you'll end up needing the extra weight in the tail anyway.
Now that all this has been said, it's an oddly fun plane to fly in that it will challenge you since you really need to fly the thing in an old-school manner. It's not a point-and-shoot airplane. You need to know when to whip it up, when to relax the pull, and when to "wait for it".
The .35S is ample power with a nice 2-4 break and that's one of the most fun setups to fly. You gotta trust it when you pull that wingover turn and down lines happen really fast!
Chuck