The Bands second album (S/T, "brown") album was once again released on LP by Mobile Fidelity in 2013, catalog no. 1-419; they had already put out a version in the 80’s, around the time of your copy of Music From Big Pink. By the way, MFSL has also redone MFBP, with improved sound compared to the 80’s version. Tim de Paravicini of EAR-Yoshino has worked on MFSL’s playback equipment, one reason for the improvement. What IS new is the brown album on a MFSL SACD. MFBP is also available on an SACD by them.
Both the 1st and 2nd Band albums have had many pressings, the best being the original Capitol "lime green" label ones---look for "RL" scratched into the run-out groove area by the label. Robert Ludwig did the original mastering, and for best sound that’s the version you want. Of course, everyone should have all three--the original Capitol lime green label "RL’s", the new (second version) MFSL LP’s, and the MFSL SACD’s. THAT’S how good the first two Band albums are!
The Last Waltz, being a live recording, and with many guests artists, some of dubious merit (Neil Diamond? Robbie wanted him there because he was producing an album with him at the time. Joni Mitchell---with The Band?!), isn’t worth worrying about imo. They were captured much better at The Academy of Music in 1971, and released on LP as "Rock of Ages", as you mentioned. I haven’t heard and don’t own the MFSL LP version, but there is now an expanded version of that album available as a CD boxset entitled "Live at The Academy of Music 1971". Another must-have is The Band’s double-LP live collaboration with Dylan entitled "Before The Flood", they backing him as well as doing a set by themselves. They are the best band he ever had, and he is spittin’ fire!
You also want the CD boxset entitled "The Band---A Musical History". Lots of previously-unreleased and rare music, as well as regular album tracks.