No offense but you have much more research to do.
The trans you are looking for is a M5OD-R2 - Specifically one that came behind the 4.2 V6. This trans will bolt up to a 302, but put the shifter farther forward in a similar location to a M5OR1 that came in the Explorer/Ranger.
Talking money - It is much cheaper to rebuild your V6 then get into a V8 swap. The v8 swap produces a great result - but I wouldn't recommend attempting any of it until you have spent dozens of hours researching on this website and
www.therangerstation.com, and are comfortable with some fairly large expenditure.
Key Mechanical issues you have to address:
Motor Mounts
New Trans
New T case or AA adapter to run your 1354
New/ modified driveshafts front/ rear
Remote Oil filter setup
Non AC heater box or notching the AC box
If you want headers, roughly $700-$800 for torque monster brand. Nearly all others will hit on the steering shaft.
Wiring is a whole different animal - and where the research comes in. There are a handful of options - all depends on your goals and what you have available.
Explorer V8 OBDII system.
Older MAF OBDI out of F series/ Mustang.
Carb'd.