MrBass,
Getting the right prop for the right plane sometimes takes a little experimentation, especially with a scale plane. Work within the recommended props for the engine and see how your plane performs. If you don't like what you have change it out for another. 12x7 may be a bit small and high pitched for the plane, but you can try it to see what happens. As for APC props, while great for speed or sport planes they just don't seem to "look" right on a scale warbird IMHO.

Hope this helps

Ken