That seems like a lot of gear, I guess it would be ok in 1/8, don't really know what to say on you eng trouble, except ether learn to do it your self or save up for a real pro to do it, spun bearing are almost always a oil supply problem, caused a lot by mods done by a builder that should stick to lawnmowers, I see a lot of eng/oil related issues caused by doing things that are of no help, and could cause additional trouble, I know what your probably saying the pros charge so much you cannot hardley afford it, thats true but look whats lost by having the motor torn up every few runs, (the week you miss you may have won, but your eng was in pieces) and then having to pay to get it fixed, if your not up to tackling it yourself, start doing some research, Steve Knecum, Bob Carpenter, and several others I'm sure, those two just come to mind as I think they both mostly do NA motors