Keys: I pulled together a good collection of catalog pages for old mopar keys when my original broke off in the lock. It took some research to figure out the rxact right blanks. The big "we can make ANY key" locksmith could not help; but once I had the correct blanks, the local hardware store (bless 'em) cut them and didn't think it was worth charging me! (That's why I will always pay a little more for hardware etc from them rather than big box: your local hardware store should know your face!)
Titles: FWIW, I registered my 41 Plym in NY State based on a slightly skanky bill of sale. In New York, older cars aren't titled, and the registration is used just like a title to transfer ownership. When I moved to Massachusetts there was no issue titling it once inspectors determined the numbers were right. So, hurray for me, but overall, getting a title to an atypical car can be difficult: friends who have bought repaired "salvage" vehicles have never been successful.
Good luck with your Vermont thing - in Mass you MUST be able to prove residency to register; but maybe VT is different. After all, VT (as well as western Mass) do have a lot of folks from NY with vacation homes up here, and I think it's a little "statusy" to park in NY with VT plates. Pretty much proves you are and older, tenured academic!