Why not just use a 31ci head or one with the normal length stud bosses? That would be much easier. I built a 33ci head for a customer before and didn't have this issue.
I suspect you didn't have this issue because they have since changed the girdle. It now has a cross-brace with two additional fastener holes for added strength, and I find it rather superior to the older version. Also the rocker-to-valve contact has been improved.
I also find the 33 head to be superior to all other OHV heads, with the exception of the exhaust port on the old 28 head. There is no taper in the intake runner. The bowl has a better radius. There is material added around the intake manifold flange area on the outside, as well as extra material across the bottom side of the intake runner for added bracing. Needless to say this and other features have caused the floor of the rocker area to be raised considerably, but without changing the length of the factory pushrods, which is why I might be over-complicating things, yet again.
I think milling the bottom of the cross bracing of the stud girdle .200" will no only save me the trouble of making spacers, and making other valvetrain changes, but will, and I hope, not affect the strength of the girdle. It's nearly .500" thick.