89 2200 v8 swap

You shouldn't have any clearance issues for the distributor. I have an 87 b2200 with a sbc with an hei. Everything has fit fine. So Far.

Distributor, being in the front on the 5.0, you can put the engine further back. That is a good thing, you will need all the room you can get in the front, good luck.
I have done a 4.3, a drop in fit (no truck modifications), just not the sound (power) of a V-8. Still, increase of 60 hpr is good, no differential problems.
Having put a 350 in a Vega Sedan Delivery Wagon in the early '80's, too much is too little fun. Much pedal in first and second, no speed gain, lot of tire smoke.
Bottom line, V-6 can be beefed up, if desired, automatic with a shift kit, it gets gone, with tire spin on shifts. Enjoy your build!