I once collected a set that way back in the early 80's.
While at car shows here and there, when everyone was running Cragars and the like, I would ask guys with hi-po 71 B-bodies if there spare was still there.
After swooning them about how nice their car was, I would occasionally sweet talk them out of it, stating it was not compatible with what they had on the car .
Once at a Quebec show I had to follow a guy almost an hour home in case he got a flat. Paid him $100.00, the most I had ever paid for an untouched 450 with a G-60.