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I am grateful for both Archbishop Lefebvre and Bishop Guérard des Lauriers, O.P. The former, everyone knows what he did for Tradition with great courage and piety; the latter is lesser known. He wrote the Ottaviani Intervention (a theological critique on the New Mass), and drafted the encyclical defining the Assumption dogma, among other things. 

I've only been a traditional Catholic for a handful of years so I'm still getting up to speed on how all the various resistance/sede groups originated and the different personalities involved.

Welcome to the party.

You might find, if you haven't already, that there's something you don't quite like about every perspective for some reason or another - whether that's some version of sedeism or the arguing between who is really following the 'true line of +Lefebvre', etc. As for myself, I was a cradle Bogus Ordo Catholic, fell away until my 30's and then returned to the diocese one Easter only to then go on a search because everything was clearly insane in the New Order. Fairly soon thereafter I found a hold-out priest who said the 'Latin Mass' mainly because I'm a musician and wanted to find Gregorian chant. From there I found the SSPX, went Resistance in 2012, and finally looked into the last great taboo of sedevacantism before and around the time +Williamson began praising Novus Ordo miracles. All this is to say - hang in there. Tradition is absolutely necessary but it can get a little hot under the collar once in a while - and that's just among fellow trads (without getting into the friends and family members who clam up when you ask, 'but what about those encyclicals by Pius VII - Pius XII, Leo XIII and XIIII, etc.' or 'How is it that Pope Saint John Paul II the Great is the poster child for everything Pope Saint Pius X condemned?' That's always a fun one that shuts down the conversation quickly).

I think that the problem here is an equivocation on the meaning of "New Mass".

Most immediately think 1969 and later missals -- the Novus Ordo Missae.

However, "New Mass" in historical context can also mean the changes of 1964 and 1967 made during and after Vatican II to the 1962 missal.

In the former meaning and putting aside the issue of concelebration, it is very doubtful that Msgr. Lefevbre ever used the 1969 or 1971 editions of the Roman Missal. No evidence exists for this.

However, in the latter meaning of what some call the "interim missals" of which no typical edition ever existed, Msgr. Lefebvre did offer Mass in the late 1960s using those changes of 64 and 67 and later reverted to the pure 1962 missal. However, he encouraged Le Barroux to use the so-called 1964 missal because it worked well in a monastic setting. Further, he recognized until about 1980 that the pre-62 usages were the norm amongst traditionalists in English-speaking countries.