Al,
Give the guys at OverKill Performance a shout, they are the ones building my truck.
info@overkillperformance dot ca
They deal with AVS. (
http://www.avsontheweb.com/home.php?cat=327 )
Instead of welding a new port onto it they can just rotate the brakets, or make you a set of custom cradle brackets to mount the tank. (that would be cheaper)
Just my 0.02 cents