The fenders, hood, cowl, basic body stuff are all compatible between 1981-1987 pickups, and 1981-1991 Blazer/Jimmy and Suburban.
The headlight and grille stuff changed within those years, so you'd have a hard time mixing and matching between your '90 and, say, an '82.
Your best match will be '89-'91 Blazer/Jimmy/Suburbans, which have the quad headlight as I presume yours does. (Some basic models, i.e. fleet vehicles, had a different grille/headlight arrangement.)
There's a tech article about updating an older truck to this style, some of which might helpful to you. Not all of it would apply since you'd hopefully just be swapping like parts for like.
http://coloradok5.com/grilleswap.shtml
Finally, removing/replacing the quarters and such is pretty easy, but hang onto the shims that fall out, as you'll need them to realign the body panels to the doors, etc, when you reassemble her.
-- A