STARTER BRACE
Following up on the post by 'kennyw'. The Starter Brace is CRITICAL, I literally wouldn't drive the vehicle on rough roads until one is installed. I've been playing with 6.2/6.5 Diesels for 25 years and have seen photos of the Starter Mounting Pad being BROKEN off the Engine Block. I think the 'Direct Drive' version of the Starter was more prone, due to it being heavier, however both versions are long and heavy. The 'Gear Reduction' version was introduced some time during production and in my opinion would be an upgrade. Just be sure to get the Brace for whichever starter you have.
One necessary feature for installing the brace is your Starter should have a Threaded Stud as one of the Bolts holding the unit together. That Stud is where the Brace mounts. If someone installed the 'Incorrect' Starter, it may not be present. There is a Threaded Hole in the side of Engine Block that secures the Brace to the engine. Also, I would follow kennyw's lead and purchase REAL GM factory Starter Mounting Bolts. All the ones from a 'Parts Store' are Chinese Junk copies.
I've had an '87 3/4 Ton 4x4 Diesel Suburban since 1998 and they are amazing. One wire to open the Fuel Shutoff on the Injection Pump is all it takes to keep the engine running. There are 'ways' of converting that valve to a Mechanical Cable, or at least there once were.
Fine looking rig, and your Mods fit well with it's mission. Not fond of 'lifts' personally, due to being an 'Old Geezer' and detesting getting in and out! Ha!
Bruce