You said that you were going to purchase an OS .46 engine......if you buy any APC prop such as the 12X6 or the 11X6 or the best : 12.25X3.75 , I doubt you are going to have to ream the prop.

For your first plane, I'd get the 12.25 X 3.75. This prop will give you the climbing power you are going to need to get out of problem situations, takeoffs will be a breeze, and also a nice slowing action when you land. Just be sure to buy more than one prop A very useful tool to purchase is the prop wrench, it can take out glow plugs, and fits a couple of different prop nut sizes.