Help!

Like Schultz "I know nothing!" (Hogans Hero's reference) - However I do have years of experience with "Normal" four strokes mainly 91's and 120's O.S. surpass.

I am finally building my dream plane a P51 with a "four" blade prop. Over the years I have been acquiring RCV SP engines and now I am going to put my RCV 120SP in a ESM P51B with the Keleo "Scale" exhaust.

QUESTION - I am having a spinner cut and not having any experience, should I go with the 16X8 or 18X10 on the 120SP? I know RCV recommends the APC 15.5 X12 but that prop is "UGLY" and won't go on any MUSTANG of mine! Plus it looks like it would cut you sitting still!

Thanks

http://www.smigla.com/english/four-blade.html