94z Door panels go on a 87 IRoz?

What will be the problem with this ? Will it even work ?

nope, won't work right out, i would say lots of modification is probably required, plus the two doors have a totally different shape, inside and out

Its been done, but it looks cheesey at best. The panel doesn't meet up with the dash right. It looks ok with the 4th gen dash as well. Do a search on thirdgen.org for "forth gen" and you'll turn up a bunch of pics, I think there is even a walkthrough on how to do it.

its been done numerous times but normally followed by a dash swap like mentioned. go to thirdgen.org and do a search. you'll find all kinds of info on how to cut and what to do