96/97 Ex 5.0 could be the better choice for your Ex because it has no PATS and because it uses a Return fuel system like your 93. The major parts you need from the Ex are the complete engine, transmission, engine and trans harnesses, PCM. Working from a complete donor vehicle would be ideal because there are always a bunch of detail parts needed in a swap like this.
The transfer case could be from the 5.0 Ex or from a full size Ford pickup or the factory 4.0 Ex t-case should be adaptable using a $600 kit from Advance Adapters. BTW, did you know that the 5.0 Ex case is single speed, full time All Wheel Drive (no low range)?
This article does not apply directly to your situation but it should give you some ideas.
5.0 Explorer EFI Swap
Some negatives:
The Ex 5.0 is OBDII and the 93 Ex is OBDI, so that would likely cause you a few headaches. Also, the wiring connectors are not plug and play between the engine compartment and the engine harness.
Using a late, mass air Mustang PCM and engine harness would be a closer match electrically speaking to the 93 Ex but it would require a distributor instead of the Explorer's coil packs.
There is a lot of info and aftermarket parts support for V8 swaps into 97-back Rangers and most of that would transfer well to a 91~94 Ex. The A/M can supply conversion motor mounts, oil pans, swap headers and filter adapters.
http://www.mre-books.com/ranger.html
http://www.rangerpowersports.com/forum/forumdisplay.php?f=12
http://www.v8-ranger.com/
http://advanceadapters.com
http://www.therangerstation.com/tech_library/V8Conversions.html
http://www.jamesduff.com/broncoII/v8conversion.html
There are also a few Gen1 Ex V8 swaps on the
Explorer boards.
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