These engines are better if you keep them in the 7,000 to 7,500 rpm range. A 18-8 would be ideal. They will also do better with a 7/16" or 1/2" carb. The stock carb is a 3/8". The origiinal magneto ig nition is OK but I run C-H ignitions on mine.

A 120 size plane is correct but you must pick one a little heavier with a bigger front end.

Enjoy

Jim