Times like this makes me wish I had more time to mess with that ranger. It was the first engine I rebuilt and there are many things I could have done differently in hindsight.
Intercooler, balanced & blue printed, proper rebore or resleeve (yes, it is factory sleeved so it can be overhauled an unlimited number of times), maybe a bigger water cooled turbocharger that later ones came with anyawy. Some one in my town was selling a rolling ranger chassis on craigslist a while ago. I went to see it just because it was 5 minutes away. But for $1200, he should have at least been able to start it for me to see it run. I didn't even make an offer after seeing the condition of what he had.
If I could find a spare engine at the right price I would be so tempted to try an upgraded build then do the swap when it was ready.
The 4D5 series mitsubishi diesel engine was used in just about anything all over asia, europe and the southern hemesphere from forklifts to small 5 ton box trucks, compact sports cars, and compact pickups. It might be an import but it has a decent record.
I have a 85 Ranger that is a factory Diesel. It has all the options including a/c, cruise, 4x4, etc. It is a rare truck and a joy to drive. The original 2.3 was worn out so I just found an importer in Canada who imported me a new Crate 2.5 L 4D56. This truck is amazing. We just got the new motor in it last week.