had this issue a few days ago purchasing another 49 plymouth they wrote down the block id not the actual vin number so I explained to them before they finished the paper work it would match up with over 50k other cars if I register it as that vin, so he corrected it. there are many things you can do at this point which are all not illegal. 1 take the actual vin number and the block id number and check if it is stolen, if they both come up clean you go to california dmv show the paper proof of sale or nevada dmv should allow it and have the title given to you. This is the gray area what you could do, if it does not show up in any records take it to dmv ask them for a form to reclaim a lost title and lie tell them it was in the family and you need a new title made for it in your name it requires all the same inspections and cost, it just cuts out the 80+ miles of dmv driving.
Should point out. For california, a master mechanic may remove and reinstal a vin for the purpose of restoring or rebuilding, also in cases of cab swaps, I learned this from my father when we rebuilt a 1963 gmc, you could check on your state and see if they will fix it all, and remember they do not need to see the car to run the numbers just write it all down first.