Hello. I have a CMP hellcat that I was originally going to power with a 120 or 125 four stroke engine. However, I would rather go with a converted gas engine. I am wondering what gas engine to convert. Will the 25cc poulan/homelite engine be good? 32cc mcculloch? Ryobi 31cc? Also, should i use a CH ignition if i do the conversion? Relevant Specs for this plane are here:

Wingspan: 70"
Length: 53.5"
Weight: 9.9lbs to 10.23 lbs
Engine .90-120 4 stroke

Thank You.