Repeating what 32vld and Martin said: You have caused more trouble for yourself. It sounds like you are giving WAY too much info to DMV. First of all, the correct info was given: Go to DMV and get a tag. I believe you know that. Sounds like there will be no questions if you are the owner of record and you have your ID (drivers license).
When you sell it, at least in my state, you would sign over the title and the new owner would go down to DMV and get the title transferred. If everyone stops mentioning about the title not matching, and you follow DMV normal procedure it will transfer. You have documentation and the story of how it got mismatched to tell a buyer. It will get sold and resold for a 100 years that way.
If your state needs an inspection every time to see that numbers match, get a supervisor to understand that the VIN plate is the way to go, obviously. Get them to change the Title to match the VIN plate. If removed by you already, make sure you reattach the VIN plate in original location without making it look like it was ever off. Do not play any funny games with a new, aftermarket plate unless you already know what size handcuffs you wear. Stick with the honest story and do honest common sense things.
Your no. 1 can't work, no Bill of Sale. If you did have BOS, still mismatched numbers.
Your no. 2 works.
Your no. 3 is an interesting idea BUT you don't have a bill of sale for that "engine" number. So that's out.
Get title to read 9HP I 15712, that is the coup de grass or whatever.
I didn't know that about 40's frame stamp that Cletis mentions. So that means GMC did and Chevy didn't...then Chevy did and GMC didn't. Weird production ideas back then.
