why not get a donor mustang, do an engine swap then just reuse the entire mustang harness? then the gauges will all work, etc. but if you are just doing the dash, there shouldn't be anything major for rewiring as you will be reusing the ranger wiring. you'll have to splice in the headlight switch, the hvac controls, etc. the gauges will be the biggest task.
oh, and here's my 03 cobra dash in my 93.
hope you have power windows, a manual trans (or floor shifted auto), and be prepared to modify every last piece of plastic around the dash. a-pillars need to be modified, and on 93+ the door panels do as well. you may be alright there on your older truck.
the hvac is the worst part. the only conclusion i have come to is aftermarket heat/ac.