"2/3A NiMh preferably in a hump pack" was the mans request as that's the space he's got to put the pack in. 2/3A is the cell size, the size used in 5 cell reciever packs. The packs you linked are about twice as long as a 5 cell hump pack. I don't know of any 5 cell hump packs with more than 1600mah, seems to be the limit of the cells. You might be able to find a 2s Lipo that'll fit but I'd just get two 1600mah hump packs so you can just swap them on a long bash session.