For the easiest time overall, just get the RC-Monster MBX6 conversion (includes motor mount, battery tray and servo mount top plate).
For the best performance/ease, get the Elite motor mount, a custom-sized battery tray, specifically made to your batteries, and you'll be there.
I'd expect you to get about 15 minutes out of the 4S 5000 pack, and the weight balance will be pretty good like that too.
The batteries you've chosen perhaps want increasing to the 30-40C batteries, but the brand is pretty good overall, and for the money, simply excellent.
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