I'm running a 77" belt on my 149 w/44A and it is VERY tight, just barely makes it on the deck. With my set-up in mind (worn mule drive and who knows what other gremlins), I recommend a 78" belt...
http://www.amazon.com/gp/product/B00...=ATVPDKIKX0DER
My 77" is also an Oregon Aramid (aka, Kevlar) belt and is holding up great. It's also hard to complain out the price.
Disclaimer: I wish you the best, but try my link at your own peril.
That disclaimer said, I'm 97% confident that a 78" will work fine for just about everybody with your setup. I also really do like that Oregon belt. It appears to be much higher quality than the Cub belts.