There are only two jets available from Honda, the #60 for the PA50I and the #78 for the PA50II.
Most jets for carbs like Mikuni are rated in fuel flow (like cc/min or some such) or bore size. The Honda jet numbers are related to the actual part number.
99101-124-0600 for #60
99101-124-0780 for #78
Certainly the #60 for the PA50I will be smaller than the #78 for the PA50II
Joew, have you ever run a #60 in a PA50II?