No one does them because they're not really worth it. A 2.3T swap is easier and usually produces a faster ranger. But don't let that stop you. If you really want to, go for it.
Basically it's the same as a 5.0 swap. Motor mounts are the same, tranny choices, issues are the same. You have more room in front due to it being shorter. The wiring swap is like any EEC-IV to EEC-IV swap. Just figure out if you can use the existing harness or if you need to try to use the SC one. If you use yours, you'll need to switch some pins on the computer connector and run some new wires for sensors your 2.9 doesn't have. The main difference I can think of is the 2.9 is TFI ignition, the 3.8 SC is DIS (94-95 is EDIS, in which case a 4.0L ranger harness would probably work well).
The 3.8 SC trans choices were the M5OD-R2 (F-150 version of the ranger M5OD-R1, an exact replica only everything is about 10% bigger) And I'm pretty sure the auto's were AOD's or 4R70W's in the later years. But then again they could be the E4OD seeing as how they were using the M5OD-R2 instead of a T5 for the manual.