The only problems I can see will be the tach (4cyl and 6cyl not compatible) and because of that the speedo as well.
In the 95 the tach/speedo are an all in 1 housing. Meaning the wires get plugged into the tach side and they power both gauges. The 91 are separate I think (not sure). The rest of the gauges are the same in both years and both motors.
The drive shafts should be the same. There is only a slight difference in length between an AX5(4cyl) and an AX15(6cyl) and the t-case is the same externally. So the drive shafts should work.
'87 YJ, 4.2L built and bored, 8.5" of lift, 8.8 rear, AX15/NP 231, Tom Woods drive shafts, Flat fenders, 12,000LB winch, Custom bumpers, Rattle can paint job. Never completed...