Hi Vincent
If you do a SEARCH for 38 Special you will find some nice discussions, most folks have powered up to 40-46 size engines. It sounds like it will do a pattern but is not a threat to win the NATs!
This weekend, I will be building a prototype of an electric conversion package for the 38 Special. I will be using the Brodak Arrowind 40 sized electric system, and plan on using an 11" prop. The power system I am using will also turn a 12" prop if needed, but I'd bet that willl be too big for the airplane to fly properly.
I'll try to post some pictures when I get them!