Dar my Blue Max sort of a WW! looking mid wing has a 13x6 zinger and flys quite nicely at "scale speed" a 13 x8 would be a little too
much, my vmar hot rod with the irvine 53 uses a 12x6-10 zinger which unloads if that is the right term and goes like a stripped ape
with that prop it would be nice to see the real speed and rpm with an onboard RCATS unit for rpm/speed meaurements but I do not have the bucks for that unit at this time martin
Also the smaller PAWs have been used in high speed C/L for years and they do state in their info sheets to check the rod after 3 to 5 hrs of run time if run at 15K high rpms in any engine requires checking after a few hrs
try and get some new ether too for your 49