The registration on that truck should say "transferrable" on the front with a place for the previous owner to sign on the back. That and a receipt for tax at DMV should get you on the road. The affadavit that on yellow paper is the one I think greg is referrring to. There is an buyer side and seller side to that one. Not a big deal unless you cannot locate the seller. I am not sure that this one is always needed when fair market value is not an issue.
There is also an affadavit that is reserved for vehicles where the chain of ownership is in question. I had to do that with a 67 Mustang that was never registered in the name of the person who sold it to me. Not a biggie.
Also, the engine number is fine. If that is the way it is on the road now, go with it. I have had clerks get all confused because the number of characters does not fill the fields they have in the computers. Telling them that they did not have that many characters in the vins in the 50s seems to calm them. Again, no issues once they see how old the vehicle is.
Allen