Thom,
I helped a buddy of mine put a 305 V8 into an 88 S-10. It wasn't as hard as I thought it was going to be, but when it came to the wiring, all he used were three of the original wires from the harness (I can't say how many for your 93) Of course he put in an old HEI distributor and used the factory fuel pump which bolts on the motor. ( he did however pull the tank and bypass the fuel pump to make sure that it didn't restrict fuel flow )
Far as using the in tank fuel pump for the carb I would be very leary of doing so. Fuel injection runs at about 30 to 45 psi of pressure, a mechanical fuel pump supplying gas to a carb only pushes about 10 psi. I don't know how well a carb would hold up to that much pressure if it was never designed to do so. Of course with that said, the best person to ask would be someone who runs/works at a speed and custom shop. They replace all kinds of fuel pumps with higher volume and higher pressusre ones, would likely be able to tell you if you can use the original or not. Make sure if you do rewire it that you fuse it, don't burn the truck or endanger yourself because you don't protect the circuit.
Now for the coil, I don't know much about the small chevy trucks, but that distributor you picked up may be an HEI (High Energy Ignition) If it is, there is a coil built right into the top of it. That would mean your existing coil is of no consequence.
You bring up a good point about the tranny, since I have never owned a truck that new it may very well be an electronic one. Which may very well mean that when you cooked the brain box it also took the tranny control's with it. Old style tranny's were pretty much self contained and would shift on their own. Your tranny on the other hand, IF it is an electronic one needs the brain box to tell it when and how to shift. You may have to ask a dealership what kind of tranny it is before you get too far into this retrofit.
Far as it being feasable, anything is.... and let me tell you that V8 motors in those little S-10 trucks are one hell of a fun ride. They now have kits out that give you motor mounts, tranny mounts and rad's etc. to retrofit V8's ( wiring too ). With the amount of crap you may have to go through (possibly changing tranny's too) it may be worth the while to look into stuffing a nice little ( bone stock ) 305 into that ride. If you put in an overdrive tranny, they even get you pretty good gas mileage (my buddy was getting 25mpg)
Anyway, I don't think I've been much help to ya, but at least it may give you some idea's.
Good luck, and if you go V8 let me know I may be able to give ya some more pointers.
Todd