I removed the GM Pitman arm and installed the Moog K6099 replacement Pitman arm on the car today and the Moog arm compressed against the header as it was tightened to the frame. The OEM arm had just over .25" clearance.
A bronze replacement bushing for rebuilding the OEM arm would be real nice in my situation.
Doug's D368 headers, GM OEM motor mount perches, Moroso 62150 solid mounts.