Dakotas, S10's, Rangers, they're all easy because you can use off the shelf parts (usually out of a catalog too)
Want a real challenge, I mean aside from the insanity that draginmopars did.... Dodge D50. No off the shelf parts fit the truck for the conversion, very few factory parts can be used (factory to the truck), stuff has to be mixed & matched to make it work.
No off the shelf headers will fit the truck (Long Tube or Short Tube, Truck or Car), they would have to be custom made for the truck after the engine has been installed.
The swap requires :
LA Car Oil Pan
Solid Motor Mounts (with the engine tilted down slightly on the Right/Passenger Side. Oil Pan must sit on top of the crossmember, or at most a 1/4" above it)
360 Truck Exhaust Manifolds
Custom Down Pipes (Each downpipe had to be made in 4 pieces for my truck, took me 3 days of head scratching to get the exhaust to reach beyond the transmission)
A Low Profile (Shorter and Smaller Diameter) Ford Oil Filter to clear the frame
A D50 Transmission Mount (Automatic or Manual)
A Lokar Throttle Cable (Cut to roughly 6" Long)
Lokar Kickdown Cable (if running an Automatic, no space for the factory Mopar Kickdown)
Requires a 70's Charger 22" Radiator, with extensive Core Support modifications (and some modifications to the inner hood skin).
You're limited to a Mechanical Fan (with no spacer), there isn't enough space for electric fans.
Transmission has to be either an A833, 904 or 727 (2WD)
If you want a 4WD You need a TF904/MA904 Hybrid (use a RARE MA904 From an Automatic D50 to install the guts in a Small Block 904 Case) OR A TF727, with an AMC/Jeep Tailshaft & Tailhousing. If you want a Manual 4WD, you're screwed, there are no 4WD Manuals that will work in a D50 with a Small Block (the shifter would be inside the dash on all of them)
If you've got a 2WD, good luck getting traction...EVER. Your best bet would be to tub it, slap some wide tires on the back, and load 1000 pounds of ballast in the bed. A Small Block 2WD D50 weighs in at about 2,700 pounds (A stock 4WD 4-Banger D50 weighs about 2,900), a 4WD Small Block D50 might go 3,100 - 3,300 depending on options. Mine's a bit more than that, with the Rollbar, Rock Sliders, Tube Bumpers, Front & Rear Mounted Winches (10k Front, 12k Rear).