Welcome to the FT forums Jessem! It's a fun plane. One of my favorites.
If this is the model you're using the parts from:
http://www.flyzoneplanes.com/parts/flza4010-parts.html
It seems to use this motor:
http://www3.towerhobbies.com/cgi-bin/WTI0001P?I=LXCLBC&P=8
With an 8x4 prop, if you build it light, it will fly well. I wouldn't go any bigger than the 2200mAh battery... in fact, I might go a bit smaller, lighter with the battery, but I think a 2.2A would be ok. The 18A esc should also be ok, but I wouldn't go into full throttle territory for longer than short bursts...
Can you weigh that motor? It looks like it's no more than 40g in weight... should allow you to balance out the Versa in a pusher configuration ok without requiring a heavy battery or too much nose weight. On my blunt nose build with a somewhat bigger motor and a 9x4.5 prop, I can get over 30minutes with a 4.4A battery. When I had built it lighter, I was able to do the same with a smaller prop and a 2.2A battery.