Seems like I recall somebody around here hotrodding a slant four with a super duty 421 head. Unless I was doing something like that or needed one head to replace a bad one I'd think the market would be infinitesimally small.

Gotta correct that, really old memories, he was running a RAIV head on that thing. I know it had to be adapted to the earlier engine, completely forgotten what had to be done. Pontiac heads have a couple or three year breaks for one thing or another.