To run 6500 RPM, I would send them and the shafts you plan to run out to Gary at Rocker Arms Unlimited and let him bush them. He will also correct for any geometry differences.
Thanks. I've used Rocker Arms Unlimited before on A-block 318 rocker assemblies, and they would be the ones I'd send this 273 assembly to if it's warranted. Their bushed and chromed reconditioned assemblies are much tighter than this .003" clearance, which is partially why I asked my question in the first place knowing if the assemblies required .003", Rocker Arms Unlimited would build that in. I might call Gary and get his input.
