I found what appears to be the same engine (in the trash!) has same #68501 above exhaust port, I raised the piston to just close the exhaust port, removed the spark plug and filled the cyl. with oil, from a calibrated syringe, until it started out the spark plug hole,and ended up with 35cc's.

I reversed the crankshaft so the carb is at the back (makes throttle link a breeze and eliminates anti-siphoning)

Stole prop adapter and ch ign. from air hobbies eng. I got from an auction ($150.00)(BOAT ANCHOR!!! good ign.)

here's some pics: