6-lug wheel hub diameter too large for rally wheels?

[badpeanut]

On both my '70 1/2-ton and '71 K5, later model wheels ('73-'87ish Chevy 1/2-ton) don't quite fit over the center hub of the axles. On some junk 15x6 steel wheels from an '80s Chevy truck I ground the centers larger so they'd clear. However I want to put a set of freshly blasted and painted rally wheels on my Blazer and I don't want to grind these. I was thinking of taking the axles to a machine shop and having them turned down 1/16"-1/32" on the diameter except where the brake drum sits (or have this done to a new set of axles because mine have tired bearing surfaces).

Anybody else have these issues? Anybody have a better idea? Any chance I could buy new axles that wouldn't require this?