Absolutely send to PHS
http://www.phs-online.com/ for original PMD info on your car. You will get all of the ordering instructions from the web site.
You will NOT get conformation on Royal Bobcat status from there, however. The only way to get that sort of information is from original paperwork that might still be with the car, i.e. receipts or invoices from Royal Pontiac stating that your car did get Bobcat upgrades.
Royal Bobcat packages ranging from mail order parts to an in-house Royal conversion were available back in the day.