You are going to need a 5.0 roller made between 87 & 93 to rob parts from. Otherwise you'll never have all the parts you need. The body shell and a few of the other parts like the K member are all the parts that are interchangeable between 4 & V8 cars. The rest of the parts are unique to either 4 or V8 model cars.
I guess I should have clarified myself. If you are doing the V8 swap, yes it would not be a bad idea to swap the K Member for an aftermarket one to lighten up the front and to give you more room to work. I was just stating my opinion on the matter.