Hello and welcome
You need to spend some time reading on here
All the weak points are addressed in various posts, and solutions.
When i got my first 6.2/6.5 i had no light diesel experiance
I have had 6.2/6.5's for the last 20 years because of the information on this site
I have rebuilt both engines, and brought a 99 Sub back from the grave
I would jump in the 99 and drive it anywhere.
PMD is the first thing to address, it needs to be on a cooler mounted away from the engine
So do some reading, add more info to your thread about the Sub and there will be lots of help if you ask for it
90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews