The easiest way I have found if you are in the OKC area is to go to the OK Tax commission at 2501 N Lincoln. Take your notarize bill of sale or MSO along with your receipts for the parts to convert it to them and they will fill out the forms do a vin check (if you have the bike) and give you your tag and you can ride it home if you want. You will need insurance verification. They seem happy to do it and it only took about 20 min. Don’t go the tag windows go to the desks on the left. I have done a YZ before but the last one I did in November was a WR450. It is not uncommon to them and seemed easy to me.