The spindle swap is easy, depends on how dressed you get the spindles, a way to seperate the the tie rod end from the spindle, the end links from the spindle and the sway bar (you need new ones), and the pinch bolt in the UCA to the spindle.
I bought new hubs since I had an 89 and the hubs had a step (larger for the rotor, smaller for the rim), I don't think the 91 has that, so the hub can be reused, but the spindle nut shouldn't be.
Spindles (I bought them from someone on the board, cleaned them up and mounted new hubs, put them on my 97, took off what was on the 97, put it on the 89...it all made sense at the time hahahaha)
End links for 93+ car (replacing the end links I bought 2 months earlier after dealing with bad ones for 11 years, ::sigh:
Hubs from eBay
spindle nuts (I bought these from rockauto, didn't like them, and the person I bought the hubs from included the Ford ones)
I used the same tool to seperate the spindle from the tie-rod end, the sway bar and spindle from the end links.
I didn't take any pictures because my camera was on vacation with the family, but I did one car in the dirt (learned from that one) and the other in a covered car port, but it was 100+ degrees, I swapped in the Sport brakes on the 89 (the end result in the swap until I do the cobra 13 inchers on the 97, then the 89 gets the GT PBRs), new lower arms (again all new on the 97, 97 stuff went on the 89, a bunch more work but I couldn't see putting all that new stuff on the 89). It was a reasonable 6 to 8 hour job, probably a lot less if I wasn't in the sun with it hot.