Somewhere in MT's installation instructions, they mention setting their links with an additional 1/8"-3/16" length over stock. Reszfab's non-adjustable links have 3/16" more length over stock as well. I'm merely transferring information here, not knowledge.
I'm struggling with this same question, since I just did a King shock lift on my FJ, with 2" springs in the back. Mike at Reszfab, along with a few other shops, argue vehemently that adjustable links are more trouble than they're worth and Reszfab offers a small increase in the length of the upper links and panhard bar to compensate for small lifts. I'm skeptical of the one size fits all approach, but the amount of change in the driveline with a 2" lift is pretty small, so maybe close enough is ok? Having read a bit on pinion angle, it sounds like very small changes in the angular adjustment have a significant effect on the resulting handling and wear. If you want to get deep into it, this is a good place to start:
The techs at the alignment shop I frequent said, basically, if you don't feel any vibration in the driveline, don't change anything. "If it ain't broke..." is generally sage advice. That said, I'm interested in the additional downtravel that properly set links might provide. I can find no information on how much that might actually be. The alignment techs I talked to prefer to have adjustable links, dial in the rear pinion angle, and then redo the entire vehicle alignment to get things set right. If you have a shop in your area that you trust, you might be better off paying a couple hundred bucks to have someone with expertise dial this in for you.
I'd be curious to hear what you find out if you end up contacting MT, or however you end up solving this.