I would use the OS 91 you can run it on the rich side and get the same power as the 60. You will note that there is not a lot of hot air exhaust cooling. You have to cut some cheater holes on the bottom of the cowling. (I will have a picture for you) You will like the 91 it's starts easly by back flipping the spinner. The OS 91 is perfect for all the TF 80" kits.. David Pinegar