Regarding the balast resistor, there is an easy fix for that - basically bypassing it and using a GM ignition module. I will post a link to the instructions when I have access to my computer.
Having the wiring done professionally will be very expensive and you'll be hard pressed to find a shop willing to take it on.
Also, go to the Class C forum and look at the Dodge motorhome thread. It's huge with hundreds of pages, but a ton of great information and lots of folks who understand these old Dodges. Ask questions there, and you'll get some extremely helpful advice.