Others that have chimed and others who haven't know a LOT more than I do, but these are my thoughts.
The 98 2.5 made better power and torque (though not by a lot, but still) than even the 95-97 2.3s, and the parts for 98-00 era Rangers are still quite available. My 1996 2.3 5 speed can manage 29.8 mpg peak (not kidding) and I have heard that the 2.5 can do the same, with slightly better power and torque, the best I ever got out of my 94 2.3 5 speed was 27.
For the ease of your swap, a 98 era 2.5 would really be best. You retain OBD2 which is a huge benefit in itself IMO, and it also means you don't have to have the donor wiring, ecu, etc for the 94 engine, or somehow retrofit the 94 to be OBD2 which would be quite the headache beyond what I can even begin to comprehend. Even in MA where these trucks are getting scrapped and junked at an alarming rate, 98-00 trucks and parts are still pretty plentiful.
The 2.3/2.5 Lima engines are quite tough... finding a 2.5 donor engine or parts truck with a solid engine shouldn't be too hard or costly, and then its a plug-and-play swap.