If only not a diesel. https://vermont.craigslist.org/cto/d/1981-oldsmobile-98-regency/6620453816.html
It's all in the eye of the beholder. There's a few guys over on classicoldsmobile who specifically collect diesel Oldsmobiles. They'd love this car.
These days, the only problem with an Olds 350 diesel is it being underpowered. Everything else can be fixed relatively simply (thicker head gaskets, ARP stud kit, external water separator). And if it goes boom a 6.2 diesel will fit right in the same location and give you 50 more HP...
Yup, same engine dimensions for the most part. Not sure a turbo setup would easily fit though, never seen one done.