RangerFredBob - I am going to try to contact CH Ignitions this afternoon - I will see if they can make? I was going to find out if it is better to reverse this engine (if possible) and use the pto (sprocket end) or the short tapered shaft on flywheel side and if porting etc is worth pursuing - I'm pretty green on all this stuff. I intend to use either gas/glow conversion or CH - ignition and not the magneto. Will post back what I find out.

Reread your post - are you going to make a prop hub yourself and offering to tool another? I would be interested. These are different engines though. Mine is 50cc with short tapered-keyed shaft on the flywheel end and 3 stepped on the pto end with left hand threads. Yours would be a 57cc. This model was actually called a Timber Bear but it is not the older 3.7ci version - only made a short time - they were total plastic junk and apparently not much of a saw but the engine sure looks good - although maybe as weak as the rest of it. Guess I will find out.