Savage conversion:which medusa motor

[naynay12]

Ok well your right after more research i found out thethe 2200kv castle is the same price and a proven setup...
I had this other idea that would give me just as good preformance wise for cheaper.
How about a feigao motor(8XL 9XL or 10 XL?) with zippy 6s 5000mah 25c lipos?
It will work out about $50 cheaper for me(I live in Australia) and should give just as good as preformance as 2200kv on 4s .

Would i have any problems with this setup?
Should i lock the 4.6 tranny?Which size feigao?What size pinion with 47t spur?