I use the same combo on allot of my 60 size warbirds, some 14/6 some 14/8 Mas props, there great little engines,

I know some will cringe but take your tach and run the engine up to max rpm adjust it with the high speed needle so your peaking you should get about 9700-10100 rpm give or take a hundred or so, then richen the engine up about 3-500 rpm, on my engines with low run time 500 on the ones that have run a while 300 is ok

when in flight the engine will unload the prop and there will be plenty of power,

also before I ever run my OS 4st engines even new out of the box, I check the valves to make sure there correctly adjusted, none of the brand new ones have been out, but a couple that I have bought off ebay were way out.

after some tweaking there solid runners, its a once a year thing so I do mine at the beginning of the flying season and there good to go, most don't even need to be touched if there low time motors, but if the valves are out they can affect performance.