I have a 64, 5 window I am starting on. The little 170 runs but want some reliability and something different. Seems everybody is using a 4bt cummins and turbo 400 out of chip trucks and bread trucks. They are super heavy though. How about a ecoboost 2.3 from a newer mustang? I can source a whole car for the electronics and trans from our connection at salvage auctions. I havent measured one yet to see if I have to modify the doghouse. Any electronic guru's out there can throw their 2cents in there.

 

I have seen Econolines with 4-cyl diesels, as well as the Ford 2.3.

The 2.3 is a wide engine due to the wide intake manifold. You might have trouble stuffing it in the dog house.

Upgrading the 170 to a 200 is an easy swap with a lot of power gain.

Here are the engines that came originally in our Econolines.
Econoline Engines