Bulk ought not to be an issue with that
As its for a different gun (but very similar to tippmanns) then you may need a little modding for the body and then again you may need modding / tweaking for your shroud
Costwise it may or may not be worth it for you as you get the benefit of a pre built item but can get air fittings cheaply and then work on mounting yourself
(Note - remember anything imported from the U.S. could suddenly go up in price with postage and any import charges - ask about other postage options, and if you add more items to justify postage then the package value goes up and you get hit by 20% import vat plus £8 to £20 handling fees
The pre made item to mount the tank below the barrel from Punishers looks like it might be too big to fit a magazine on as well. Theres an on/off switch to the side of it will will interfere with the mag well.
Costs can be a problem, however a few buddies of mien are all looking at ordering parts from Punishers for various markers. Postage and import duty/costs would be less if split between three or four of us.