Congrats, man. I don't know much about the proofs, other than I'm assuming they are precisely what they're called. There often seems to be a handful of proofs for any given oddball set that are running around out there.
It does look like the 1973 to me. The 1972 was a test set without the pink border for Mays, whereas the 1973 had the pink border. The 1972 also tends to be a lot harder to find.
I have both in my Master Mays set, here:
https://www.psacard.com/psasetregist...timeset/290520
PSA also has a writeup on the 1973 set, here:
https://www.psacard.com/cardfacts/ba...andy-lids/4774
I'm sure there are probably a few other threads around here talking about both the 1972 and 1973 sets. Looks like there's at least one here:
https://www.net54baseball.com/showthread.php?t=217202
And another here:
https://www.net54baseball.com/showthread.php?t=110549