LSP- I know most guys like 4 stroker in a bipe, but, I think u will like the performance with the 65AX, and find that it is more than enough motor to do anything u want with the plane. When u start assembly, do urself a favor, and take a flashlight, and look up inside the frontal area around the firewall, and check the glue joints all around the firewall, and any support pieces attached(ie triangle stock). If u need to add anything, u should be able to get at it fairly easy before u put anything else in the fuselage. If u looked at my repair thread, u can see that i still had to add another 1/4" ply plate to the new 1/4" firewall to get the prop right where it had to be for proper cowl fit. I used an OS #913 alum motor mount and the OS 61SF mounting holes were exact on that mount. If u needed to add any nose weight, a suggestion would be to add it to the open pocket recess at the bottom of the fuse, and make a cover plate like i did on my repair. I don't think u will have a balance problem, after adding the extra ply to the front end, and there should be a minimum of difference between a 4 stroke W/ muffler, and a 65AX W/ a Pitts muffler. Let us know how ur model looks after u unbox it, and what u think of the overall construction. If u need anything in the way of suggestions, or ideas from us, please let us know, and we'll be glad to help. Keep us posted, and good luck. Sorry to hear of the discontinuance of this plane, it is definitely a WINNER. Thank God I bought an extra complete plane, as well as another set of wings and some other spare parts. Dean