Since you have a 4x2 it will be easier but not easy.
You need the engine and transmission, plus the computer and wiring harness from the donor vehicle.
1995 was the year Rangers got the new computers(EEC-V, OBD II), so your '94 was the last year of the EEC-IV, OBD I.
So I would stick with the pre-'95 system, the F-150 years you mention would be fine.
I think '94 was the first year F-150s used the MAF(mass air flow) sensor system, previous years used Speed Density(MAP sensor) system.
MAF system is what you want to go with, especially if you want to do upgrades to engine.
Speed Density system relies on Factory tables to set air/fuel mix, so it is pre-set for one cycle = 5.0 liters of air = add XX amount of fuel, to add power(upgrade) you add air flow, i.e. a bigger Cam, Speed Density system has no way to "see" the extra air so you wouldn't get full power from the upgrade.
MAF sensor system uses 'on the fly' air/fuel mix, totally based on air flow thru MAF sensor, so you gain full benefit of any upgrades.
While IMO, fuel injection is the only way to go, if you go with a carb and HEI distributor you can eliminate the computer all together, it does eliminate a significant level of wiring.
Automatic or manual?
Automatic is easier because of shifter but manual can be done, you may need a later model M5OD-R2 to match Rangers current shifter location
You will also want to change the rear axle if it is a 7.5", doesn't need to be right away but the V8's power will be hard on it over time.
You want an 8.8" which came in the Rangers with 4.0l, but some 3.0l had them I think.
Look on the drivers door tag for which axle you have, read here: Ford 7.5 & 8.8 Inch Axle Tag & Door Codes
You also may want to go with different gearing, i.e. 4.10, and Limited slip(trac lock) at that time, and even rear disc brakes.
Because of the limited room you will want to go with an electric fan on radiator(eliminate the belt driven fan), and a remote mounted oil filter.
The upper intakes on the 5.0ls can be taller on F-150s, so explorer upper intake can be used, or a body lift