The mechanical parts will work but the finders, hood, grill bumper and attaching parts may not, you will need to remove the old one and see if the new parts match to the bolt up holds, you will need to be sure the body lines match as well (creases), It would be better if you purchased another one in the same year for a perfect fit. Auto Body Supply in Sun Valley Ca will likely have new parts (aftermarket0 but it will save you time with the right part, Good Luck and God Bless
Yes it will fit. They are the same car. GM just updated the grille etc. on the newer ones. Make it look newer without retooling the line. The biggest difference is the header panel. Grille, & head lights mount to it. Hood and fenders are the same. The wire harness might have different plugs as well.
89-90 Caprices are in their own bracket when it comes to interchangable parts. I'm pretty positive that you should be fine as long as the front end you are trying to get is from 80-88. I have an 89 and it's quite a pain trying to find parts for it and I only have those two years to find and choose from.