The Omnorizons were good cars for basic transport. My main beef with them vis-a-vis the VW Rabbit/Golf (early ones had Rabbit/Golf drivelines) was no diesel-unlike the VW, Ford Escort, and Shovette. I have heard it's possible, with a little fabrication, to swap a VW engine and trans in them and the little mini-pickup 024 with a VW TDi and five speed would be cool.
But they would run longer than the owners wanted them to usually.
The Slant 6, despite its three main bearing lower end, is a pleasant enough engine and it's a shame there never was a small enough, and rustproof enough, chassis for them to shine. With three sidedrafts and tube header exhaust they would be pretty swank. If memory serves they have a different bolt pattern than any Mopar V8 and to add to the misery unless they were sold with a manual there's no crank pilot hole, which is a pain in the ass to have drilled out because it has to be done on a lathe rather than a crank grinder.
The asymmmetrical XNR would make a great kit (hint,hint.)
As I remember, the Nissan SD33 was sold by Chrysler as a "Chrysler Nissan Diesel" (replete with a so-embossed chrome rocker box cover) and it had a standard Mopar bolt pattern. Was it that of a /6 or one of the V8's? These were sold as a Chrysler Industrial product and not put in cars but Tony Capana did a bunch of swaps. They suffered from lack of a 5 speed manual or a four speed Torqueflite but today that would be remediable. One of the old Valiants with the trunk lid reminiscent of a Westinghouse 45° washer would make a good host for one of these great engines,especially if someone could figure out how to get a pushbutton transmission controller to work with a four speed Torqueflite.