with 5s5000 lipos use the larger dia prop or she'll be fighting for lift and speed in hovers and harriers. The plane will handle heavy with a 5s5000 pack also. My 5s4000 fly better tho I get about 5 min of fairly hard 3d with them.
don't go to a gas engine on this. You'd have to do some serious reinforcement with extra wood and it would weigh way too much.