Andy 73- Welcome to Autopia!
I would *NOT* wetsand that. If it's original paint the important thing is to maintain it so it doesn't need a repaint. Better imperfect original than perfect-but-repainted

Wetsanding, even with 3-4000, would take off *much* too much paint for me, and the paint is very likely already pretty thin in certain places. And the sanded areas will probably look *very* different from the unsanded ones. Better to rejuvenate the paint as gently as you can.
IIRC, all GMs of that era had lacquer. Meguiar's stuff would be my choice also. IME old lacquers can really drink up Meguiar's "trade secret oils".
I wouldn't use anything harsher than #83 DACP. If it won't "come back" then I'd just live with whatever improvement you can make. I'd go something like #83/#80/#7 (or another of their "pure polishes")/carnauba wax.
I've had good results from pre-treating old lacquer with #7 (this was originally suggested by Mike Phillips when I was refurbishing a '75 Jag with terrible lacquer paint). Wash the car and clay it, then dry. Apply #7 very liberally, and I mean *use a lot of it*. DO NOT buff it off, just leave it on the paint overnight. Go back the next day and buff the #7 off as best you can. *THEN* start polishing. The oils from the #7 will rehydrate the old lacquer (at least temporarily) and you should have better results polishing it.
Old lacquer is different from today's basecoat/clear finishes. Stuff like "feeding the paint" isn't all BS with lacquer the way it is with b/c. The old-school approaches are often still the best when it comes to old-school paint.