Mike, you are correct...
Yesterday was a first class feast which took precedence over a Second Class Sunday. The next time May 1st. happens on Sunday, it will be the same occurrence, except not necessarily on the fifth Sunday after Easter, due to the variation of the date of Easter.
The simplification of the rubrics had no effect in this case. It was simply the issue of Pius XII establishing a new feast in the calendar, which happens to be ranked first class.
Some further nuances...
If May 1st. is Ascension Thursday, St. Joseph the Worker is transferred to May 2nd.
If May 1st. is Easter Saturday or Low Sunday (first class Sunday), St. Joseph the Worker is transferred to the Monday, May 2nd. or 3rd.
I think he said that in 1962, first, second, etc, feasts were abolished, but I wouldn't be surprised if I'm 100% wrong about that.)
Here is one reason why you can't go by the Fr. Lasance Missal or most Missals for that matter:
Prior to 1961, Sundays and Feasts were ranked as follows:
Double 1st. Class
Double 2nd. Class
Greater Double
Double
Semidouble (this was actually abolished in 1955)
Simple
Effective Jan 1, 1961, Pope John XXIII abolished the above and replaced it with:
First Class
Second Class
Third Class
Fourth Class
Furthemore, all but three Octaves and most Vigils were suppressed in 1955. Hence, the Octave of the Ascension no longer exists, for example. So, next Sunday is properly called the Sunday AFTER the Ascension, no longer the Sunday in the Octave of the Ascension.