Looks very similar to the Wilcox Critten Winner we have been using for 37 years and would not change for anything.
It's definitely a PHII...If you look closely you'll see a great deal of difference between it and your W-C Winner...starting with, the PHII is plastic, the Winner is bronze. Leathers have given way to rubber and neoprene...no packing gland
in it either. No foot pedal for flush water
...and unlike the Winner, made to last only 20-25 years instead of a century.
Do you know how old your Winner is? I've been working on a history
toilets. It's generally conceded that W-C made the first piston/cylinder manual toilet, but apparently no one is still alive who knows when or the model name of the first one. The earliest W-C catalog I've been able to locate (the rest were apparently lost
when Thetford bought W-C) that includes toilets is 1935 and doesn't include it, but does include the Imperial and Junior, which did come after it. I would swear that the Winner was the OEM toilet on some 1920s Trumpy yachts, so that prob'ly only means that W-C had discontinued it by then. It would be VERY helpful if you know the year of mfr for yours.