It wouldn't surprise me at all if that Rimfire can handle 190watts constant.

I think it will be just fine on a 20-30oz park sport-type park flyer.
Trucker, it looks like a good combo there.
I do think you would be better off with a 20-25c 1350mha 3cell pack though.. try these...
http://2dogrc.com/ecommerce/os/catal...nt-p-2178.html
I have a few for my 200watt Airfoilz Yak and like them a lot.
They will stand up nicely to your 190watt system without getting hot and you'll get good punch and run times.

Trucker... Here's the thing... Electric props are very different from glow props, and you need to use a electric prop so that it remains efficient.
Doing just the voltage and Kv math will not yield accurate rpms either - the Kv rating is a no-load number.
Either way, your on the right track with that Rimfire... small prop, high Kv motor will emulate a little nitro pretty well.

I know getting into electrics is daunting... just keep reading and fooling around with it. It will all come to you.
You'll also find that there is a big expense hump to get past, but once you have lipo's and a couple of chargers it gets much cheaper and easier. Start off with good packs and a quality charger.
I really like the Cellpro 4s lipo charger/balancer from fmadirect.com... absolutely excellent little charger.
http://www.fmadirect.com/Detail.htm?...218&section=45
Dont forget to grab this adapter...
http://www.fmadirect.com/Detail.htm?...271&section=45