If it is the standard Zone VI, I think it would be even more rigid than the Ultralight, so there should not be a problem with using reasonably large and heavy lenses on it (don't try and put a 405mm f4.5 Kodak Portrait Ektar on it- that will wrench the front standard off of just about anything that takes less than a 9" lens board and/or has movements, but you get the idea). Heavy is relative. I think the non-ultralight Zone VI was somewhere in the 12-13 lb range - it's definitely NOT a Calumet C1 "Green Monster", which came in at 14 lbs no lens for the magnesium version, 17-ish for the standard aluminum one.