OK, so it's non-Mopar - feedback needed on a Chevy 6.5L Diesel

I have some experience with a 6.2 which is pretty similar (predecessor) to the 6.5. In general they are pretty reliable and have decent torque but are slow slow slow. Buddy of mine has an 83 g30 Chevy van with the 6.2 and he is the original owner and the only thing ever done to it was it blew the headgaskets at 1600 miles, got it fixed under warranty at the dealer and they put brand new head studs and never serviced since. He has been tempted to turbo it in the past to wake it up a little but always backs out to keep it stock. He was a commercial diver and has towed heavy *** compressors, hyperbaric chambers, and boats and the van never complained.
the 6.5 will likely have a turbo and should be a little faster but you will also have a bigger van