Off the shelf, I think the '72-75's were best.
D44 rear, D30 front axle. D20 xfer case.
72-75 is longer than 71 and earlier, about 4" longer in the engine compartment (pre 72 fender came down to a point where it joined the tub, 72 and later, it levels off for 4" before getting to the tub seam). This was to accomodate the AMC sixes. Makes much better for future engine swaps. 4" more wheelbase also slightly better for handling on road.
in NC, 35 years no inspection at all is required. 72 is very close to that. couple of more years, you'll save $10 per year.
No emissions either in many areas. No restrictions on motor swaps (cept in some areas, if you put in say a 2003 motor, you must meet 2003 emissions requirements.
The AMC sixes are torquey motors for the size. 258 of course much better than 232. Really wakes up with HEI ignition and Weber 32/36. You can do junkyard HEI real cheap if you look for the parts, or spend the $$ for a bolt-in online. Seven main bearnings in the sixes (one between each rod on the crankshaft) they will last forever as long as you maintain and keep oil in them.
Think of T18 swap. not terribly hard to figure out. Gain Low 1st if wide ratio trans. Autos ain't great in a 5 due to already short driveshaft lenghts.
4" lift is about the max I feel good with at freeway speeds. Last '5 I bought was a 74, had a springover on Rancho 2.5" springs, was WAY too unstable. Reversed the SOA, handling (and looks) improved 200%. I'd go maximum 4" springs, or 2.5 spings with a 1" polyurethane body lift. Looks better too...they look goofy if you go too tall.
With 2.5 or better springs, 33x12.50's are a great fit, looks balanced. If you go 35's, especially if lockered, you have go go easy on the skinny, or plan on either a D44 front or Warn heavy duty axleshafts on the D30. I've run 33x12.50's for 20 years now with no ill effects. if you go SBC or 360/etc, you can bust up a D30 easy with 35s and a front locker.
FWIW, YMMV, IANAL, ETC