I have some Clinton Panther information.

[sparkwizard]

My Panther 500 cane from a Sears generator. and I swapped in a crankshaft from an A400. The aluminum flywheel from the generator is pretty light. It runs, but I need to idle it fairly high to keep it running smooth. I have the iron flywheel with the A400, but that is another project. I was advised by a very knowledgeable member here that an outboard boat motor flywheel might work. I found a bunch of them on eBay. I bought a flywheel from a 77-80 2HP Clinton outboard for 20 dollars and it is identical to the aluminum Panther flywheel, which can be very hard to find. The little engines wind up a lot faster with the lighter wheel.
I might list my spare for sale if anyone is interested.

 

[sparkwizard]

I also have a D25 chainsaw engine. It is the same displacement as a Panther, uses the same piston and rings, but has no governor, produces over twice the horsepower and spins the other direction. With my spare A400 Panther, I have a tapered crank from that generator. I plan to remove the shroud and recoil from the saw engine, remove the flywheel and see if the taper is the same on the magneto end of the crankshaft. If the flywheels interchange, I can swap the point cam, flywheel and recoils to make the saw engine spin CCW. Then, if I want to, I can install the A400 shroud on the D25 and have a 5 or 6 HP Panther sleeper. I can also swap the saw magneto parts onto the A400, and have one CCW Panther (the 500) and a CW Panther. Still looking for a 5/8 PTO crankshaft for a 500 or an A400.