If you live in a small town, go to your tax assessor's office. If they don't know they can call the DMV. Or if you are near Austin, the DMV is on Parmer just past Dell Computer.
But there is no one at the DMV that remembers that a 53 was titled by motor number. All you can do is stamp the motor number to match the title. Thats what was done 60 years ago and thats all you can do now. When we bought GMC short blocks in the 50's and 60's, they came with only the 3 digit displacement and the installer stamped in the rest. We usually replaced 228 motors with 248 short blocks. In fact in the late 50's, 228 short blocks became no longer available. We ground off the 248 and stamped the motor number to match the title.
Don't even try to change the title to the number in the door jamb. You will have to do any title transfer in the tax assessor's office in the county where you reside. All they are concerned about is the sales price so they can collect the 6 1/4% sales tax and $28 title transfer fee.
