Which engine would be easiest for my swap?

The electronics are very similar on both, except like goldduster318 mentioned one has OBD1 and the other is OBD2. Neither one is "easier' to wire in for a conversion swap. They are similar, although the 99 will have more wires you will not use that were for transmission control.
The intakes on both of these will be aluminum and very similar, except the 93 will have an EGR setup and the 99 will not.
The biggest question on which engine to use will be the actual condition of the engines. What is the actual mileage of both, and what do they look like inside? A Magnum with 150,000 miles that got oil changes every 3 months or 3,000 miles will have less wear than a 50,000 mile Magnum in a 1 ton truck that only had two or three oil changes it's whole life because it was a work truck nobody cared about.

What transmission do you plan to run in the car?