What size U bolts did you use? I picked up some 1/4in ones only because that was all they had... I suppose that unless I am planning to cook 1500 lbs of meat at one time they should work fine.
I am going to try and get some SS nipples for my vents today and a riser. You mentioned that you have 3 x 1 1/4? What temps are you able to reach with that? Do you have any problems with water getting into you riser during a cook?
There is a local SS distributor around me that may have some ss expanded for my fire box. If they become a reliable source of all things SS I will let you know.