I would recommend a 2 cell li-ion and regulator instead of Li-po, Imho much better these are what I've been using for a few years, Metal cans are a bit tougher.
http://www.fromeco.org/shop/shopdisp...asp?search=yes

Also if your not, already using li-po or li-ions why not skip those and go to A123 Li-fe cells, no regulator needed, do a search here and on RCG they are the latestest and greatest.