I’m not a 6.2 fan so my knee jerk answer is 292. That said, one of the motor mounts is offset so you’ll have to get the correct crossmember that will reposition that one bracket.
Spacer between can lead to cracking or a bending in that area if the crossmember ever hits anything.
Also, lowering the crossmember will make the front driveshaft operating angle worse.
I have power mirrors but I’ve never used the LMC stuff. I know Dorman makes replacement heads only that are actually marketed for GMT400’s but they’re the same as the 90/91’s, it’s nice to see the bases are now available.
I wonder if they offer the switch too?
Embarrassing update; I’m killing a lot of time trying to flush my cooling system, this stuff looks like it came from an orange clay mud puddle. This pic is of the 5th drain, it’s got Blue Devil flush in it now that I’ll run a little more and then probably buy more to do it again.
I don’t know about the a/c compressor fitment but Kwik Performance makes adapter plates to use SBC serpentine brackets on a BBC. Everything ends up nice and tight and your existing alternator and put/s pump should bolt right on.