Just to say it first: I will be getting an MM K-Member et al in the near future....
Therefore, I went ahead and went with the 96up spindle on my 91 Fox with a stock K-Member so as to not have to buy 2 different sets of spindles. I wasnt going to spend the time, money, and effort on this swap without using an MM bumpsteer kit. I used part# MMTR-1. Seriously, its $140 and well worth your money.
I also used Steeda X2 balljoints. With the adjustability of the bumpsteer kit and the taller X2 balljoints I was able to keep bumpsteer near ideal (as measured on the MM bumpsteer gauge). I believe I did have to buy a smaller bolt (length wise) because I had to use just the small spacer along with a very thin .020 or something shim.
I could only get minimum caster on the car with 2.3 degrees right and only 1.9 degrees on the left. I cant remember exactlly how much camber I ended up getting but I know I wasnt satisfied with it.
It's not an ideal setup but the car drives great and has very very little bumpsteer. I have yet to have it on track with this setup, but along with the wider 275 tires I have no fear that the car is any slower than prior to this swap. I will have an MM K-Member hopefully sooner rather than later but this setup will suffice in the mean time.
All this being said, if you dont have any plans of going with an MM K-Member sometime in the future, I would go with the 94-95 spindles and sell the set you have.