for a plain bearing 40 try a Sig Midstar 40. They work just fine on a plain bushing 40 or 45. Easy to build and fly easily. The Tiger II or the 4* 40 would also be options. Your sportster would be better with a BB 45 in it. A bushing'd 45 would fly it. But not up to it's potential. Good luck. Oh yea a Grerta Planes easy sport would probably do. I have built or have kits for the above not the Easy Sport. I hear they are fine kits.

Mark Shuman