As far as I know, Plasti-kote auto paints are no longer generally distributed in the US. Dupli-color has replaced them across the board.
I've found Plasti-kote auto primers on Amazon (their spray nozzles are far inferior to what they used to be, and to Dupli-color) and have seen reference to the PK auto paints themselves being available in Europe.
I think the only thing paint should be matched against is old 7173 (PK's interpretation of GM15, rather than actual GM15). When TNG/DS9 concept art and painting guides mention paint codes, they refer to Plasti-kote 7173 (and other PK colors) directly, not the universal code.
It was often mentioned that PK 7173 itself had a formula change about 15 years ago, making it darker than it was before, and so even that is not necessarily a perfect match to the original TNG/DS9 props. I don't have any 7173 from the 1990s to compare directly against 7173 from the 2000s so I can't confirm this, but when I say "old 7173" that is what I mean. Is that what your 7173 is, or are your cans from the 2000s?
I do have a screen used piece from season 5 TNG but am not sure it is the original 7173.. will post a comparison later.