As long as the specs are correct, this Hyperion pack should fit nicely:
http://www.allerc.com/product_info.p...oducts_id=4649
Specs say it's 84.7mm x 27.8mm x 17.9mm
It's 1800mAh, 35C and for $30.95 looks like a pretty good deal (when they're in stock, that is).