I was finally able to grab the infamous K 50mm f1.2 and...
Oh my God! It's full of stars!
The serial number is 1200322, so I assume it's one of the first they made, as in the brochure I have (from 1976 I assume) the lens is 1200914:
I also spend an extortive amount of money for the original round hood, but as my camera tech says:"you only live once' (the gentleman is in his 80s).
The lens is a big beast...not as big as the Canon FD 55mm f1.2 but bigger than the FDn 50 mm f1.2, here there's a comparision with the 1.4 and the 55m f1.8:
Of course it landed in front of my K2DMD and I'm testing it right now.