I'm looking at buying a 5 gallon corny keg to ferement in - I'm coming from the Picobrew world where we fermented in 1.75 (AEB?) corny kegs. I own some 4psi PRV valves from that setup, and would like to use them for spunding. Would they be compatible with other brands of kegs? I'm looking at AEB, AMCYL, and Torpedo.