I can't say for certain, but I believe you will need to use the drive shaft flange from the Explorer, I believe that it has a larger bolt pattern than yours does. I know that the flange on my 98 Explorer 8.8 had a larger bolt pattern than the one on my 86 Ranger 7.5. Not sure if you can just swap the flange or not, I'm swapping in the entire 5.0 drive train so I just took the complete drive shaft.
As for the drop. Yes, the Explorer axle should get you about a 5" drop. I can understand this being too much, I think it would be for me as well. Installing the explorer springs to bring it back up the results will vary. There were 2 different heights of leaf packs installed on Explorers one was the same as the stock Ranger, the other was approximately 2" taller. From what I've heard the shorter could be found on any Explorer, the taller pack was most commonly found on the 4 door Explorers. If he has the taller pack you'll end up with about a 3" drop, if he has the highest spring rate of the shorter version I suppose you could possibly end up with about a 4" drop. So you may or may not get the lift you want from the Explorer springs, if you don't the next best option is the Chevy shackles, they will get you around a 1 or 2 inch lift depending on the mounting hole you use.
When I stuck the explorer axle under my frame, I took the springs as well. At that time I didn't know about the potential lift, so I also put in the Chevy shackles. It wasn't until a few months later when I was researching springs to replace my nearly flat ones on my 99 Ranger that I found out about the additional height, sure enough after swapping out to the 4 door springs I was able to get rid of the factory lift block and stay same height. Now I think I'm going to have to go back and remove the Chevy shackle and possibly swap the springs out on the 86 to get it the height I want. First I got to get the truck put back together to see how it sits with weight on it.