It's Classic Army, the gun come with Deans as standard with a Deans to Mini Tamiya adapter.
I would be using a 2S 1200-1300 mAh battery - room is limited in the stock due to the metal slider bar assembly. 3S is fine apparently for the gearbox, but I have heard of Classic Army Mosfets blowing quite quickly, so I would keep the overall wattage down.
I only ever really use Hobbyking Turnigy LiPos, but they don't have any 2s LiPo stocked in the UK Warehouse.
I've tried Vapextech, but they just don't hold the voltage under load compared to Turnigy.
Giant Power is pretty good from what I've heard - I know a few RC guys that use Giant Power packs on model aircraft. They've been around for a while now, I would be reasonably confident that they can get the job done for Airsoft guns.
I reckon this one will fit the gun, but I would get a ruler out and double check the stock internal measurements before ordering.
The S65 is still a really good charger for the money. Whilst there are some fancier looking units (and complete overkill for Airsoft), it's still a solid choice.
Thanks for the advice everyone I’ve already got a sigma eq charger that I can use, will get a few packs from componentshop. Looks like battery packs will fit have to ask is it a mini deans connector that is used thanks again everyone ?