How does one tell if you have the post 1999 or the pre Europiccola?
Are you asking on the two units pictured above? Which is a 49mm and which is a 51mm?
The one on the left has the double switch and also the shoulder slope of the bell on the grouphead is longer and not as sharp as the one on the right. That tells me that it is a pre-millennium Pavoni and should be 49mm portafilter.
The one on the right has the single switch and the shorter bell housing on the grouphead which is indicative of the post 2000 Pavonis and should be the 51mm.
I have bought new portafilters for older pavonis
that I needed to grind down the ears on so that they would fit the grouphead properly. But I have never bought a portafilter that was designed for a Pavoni that was really sloppy. That being said; are you fitting the portafilter w/o a filter basket? Then of course the fit will seem really loose. Also a 49mm filter basket will not fit over the screen area of a 51mm pavoni grouphead. A 51mm basket will barely fit past the bottom of a 49mm grouphead if at all
. You have baskets and a portafilter it shouldn't be that much of a challenge to figure out... Especially if you have a tape measure. Am I missing something here?
Additionally no 2 baskets are exactly alike at all... If you were to have Reg turn you a tamper at say 49.4mm then chances are the tamper is going to get bound up in the basket fairly near the top. But as a comparison a 49.0 will go all the way to the bottom of every basket. So the larger you go in diameter the more likely you are to get tampers that may get bound higher in each basket. I have a 49.4 for my Creminas and I use Microcasa 'A' Leva baskets exclusively. In most of the baskets the 49.4 hangs up about 2/3 of the way down in the basket but is a near perfect fit for my dosing. However in 2 of them it hangs up halfway down. In the Pavoni baskets that I have on hand for my Pavonis it binds up 2/3 of the way up on one and half way down on the other. So as I say it is your call but if you are going to own say 3 - 4 baskets then you might well want to stick with a 49.1mm. So if you are sizing for a 51mm pavoni basket and you want to be safe... I would suggest a 51.1... JMHO
(No longer a lever purist!)