There are a number of specific Super Cub threads here and elsewhere. Many owners on those sites have already gone through the exact replacement items needed. However, I can tell you that switching to brushless would be not be the first thing that I would do. I left my "standard" cub motor on; switched to LIPO batteries..and found great improvement. Since you will probably go that route sooner or later, you might just want to start there.

regards, Rich