Where can I purchase 360cc tank for a 25 cal Umerex Gauntlet? Do I need new reg?

I'm trying to purchase a 360cc air tank and new reg for my Gauntlet. I tried airtanks for sale.com and they were out. To be fair, they may have had the tanks but not the regulator and put me on a list. Do I even need a new regulator???? I think that I can increase the regulated pressure with shims, just wondering if there's anything different about a new regulator? Are there any other places to purchase this tank?