Mark the book doesn't suggest any different prop sizing between break in & flying. Just the prop ranges for the three categories of flying Sport, Scale & Aerobatic. For that engine under Sport your 14X8 is the last one listed along with 14X6, 13X8, 13X7, & 12X8

It does say that for the 1st ten minutes of running time NOT to exceed 4,000 RPM & to oil the pushrod tubes & the rear pressure fitting then flip it over several times to get everything lubericated before you run it. I skipped this step on my 100 & thought I crashed a valve.[:@] Then I took it apart & oiled it & re-set the tappets. Then it fired up on the second flip, go figure. I got lucky for being stupid & not reading the manual until after I tried to start it. lol

If you still have your Manual for it just go to page 16 for the prop sizes for the kind of flying you intend to do with it. If you don't have it PM me and I'll look it up for you.