Any vehicle driven on PA roads must have insurance. While plates match the cars vin, they belong to the owner who bought them. Therefore, if you buy the car no tags are required until its road worthy. Your Dads insurance is only good for you if you are listed on the policy as a household driver. Usually a spouse is on the policy which is why the Jeep was able to be tagged. He can call his insurance to list the car under his insurance, but why bother if it cant be driven? Usually with antique cars you just transfer the title. When road worthy you go to a notary and get tags for it after showing proof of insurance. AAA will guide you thru the tag process when road worthy. Only title transfer is necessary at this time. If you get the tag with the car you can reregister it as yours at the notary when you show proof of insurance and the transferred title.