I would put the 11x7 back on it, maybe go down to an 11x6, but a 10x6 is pretty small for that engine. No sence running too many RPM, you will shorten the life of the engine. (I was getting over 11,000 RPM with an 11x7 on an Evo TPS engine)

As for spinner, I would not make it as wide as the nose. It sounds like it would "fit" but in reality, it will look silly. Go with a 2 1/4" or 2 1/2" and no bigger.