Tom,

The spinner is set by the airframe, what fits the plane, either fitting the cowl, or just looking right. The engine size doesn't really matter when picking spinners. (well, with in reason. I don't think I'd put a 5" spinner on a .15 engine).

For prop, feel free to mess around and try a bunch of different sizes. What prop to use depends a lot on the airframe and your flying style.

Check the directions on the engine for a place to start, but don't be afraid to try props that are even a little bigger or smaller than the instructions say.

A 10x6 on an OS .46 is a tad small, but not out of the question. You'll get a lot of RPM and noise out of that prop. You might try an 11x6, or 10x7 or 10x8, depending on what you want to do and what the airframe is.

I'm running a 12.25x3.75 on a TT .46 in my Sukhoi for example. I also tried a 12x4, which was ok, and an 11x6 which I didn't like. I didn't bother with a 10x7, since that would result in a higher airspeed and less climb than I wanted with my Sukhoi.