Unless you put some serious money into the Chevy, you will be losing horsepower, and will have to manufacture a driveline.
Good condition M117 engines aren't in short supply at all, just a bit pricey. I'd just put another one in, or get the engine work done. If you do the work yourself, you are only out a valve job on one head (if the chain broke on starup) or both heads (if it broke running), probably new cams and rockers if you have lots of milage, and a new chain. Worse if you managed to punch a hole in the front cover when the chain piled up. Parts cost is horrible, and I think you will be ahead when you are done.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!