A friend of mine did this also. 88 gt 302 dash, engine , all into a ( I think an 84 gt) He had to change the steering coulum, and I think the whole wire harnees was swaped to, front to back. His email is
brownsmustang@aol.com or
brownmustang@aol.com he might can help you. Try both emails one of them is right. Hope this helps.