TwistedMinis
+1y
The 289/302 route would be a good bet. Aside from the SBC, its probably the next most affordable small block to build. There really isn't that big of a difference, people just make it seem bigger. Depending on who you buy from, you can build them for similar costs, or outrageously larger costs. Probably wouldn't be a hard swap, parts are easy to come by, and it would have a lot of power.
If I had a Ranger (and I seriously consider a squarebody every time I see one) I would love to run an early I6. Like the 215 or 223. Edelbrock makes lots of parts for them (head, intake, dress up), you can run dual carb manifolds, a nice cam and a new head and reportedly pull 30MPG in a light vehicle.