prop load has been discussed here in great detail. read thru some old threads. You can "search" for them.But briefly the 10x8 will be too hard for the engine to turn in the rpm range you need to get good power output. The variables you need to consider are
1) more diameter= more thrust
2) more pitch= more speed
3) more prop load= less rpm (and maybe less thrust and less speed.)
4)prop load = diameter cubed * pitch (d*d*d*p)
I have posted a web site that calculates these for you in an old thread.
Also you can cut down the props you have to get desired effect. Make sure you rebalance them.