Hi John,
I don't know what other problems you're talking about solving? I solved them all myself before closing the company. Frankly, all you are doing is putting someone else's engine into someone else's helicopter, and all the problems that in it's self will bring over the next years of testing. Sure, that is a challange all in its own, but nothing compared to starting from scratch and designing and building your own project from the ground up.
As for the tail-rotor gearbox key bearings on the shaft, they just need to be greased yearly and no problem, or just replace them with the two brass key-stock like I did years ago. As for any other problems with the Mini-500, all were solved with the Mast Support Upgrade. Sure, there has never been a perfect helicopter designed as of yet, so there is always room for improvement to any design, but that don't mean that the original with the upgrades was bad, in fact it's still the best in performing and smoothness in every way I know of.
Nevertheless, good luck with the project.
Dennis Fetters
Designer of the Mini-500