If you find someone at the DMV that will alter a title, you are very lucky. Most DMV offices don't differentiate between antique vehicles. Every tax assessors office in Texas has to authority to do title work and there are 256 counties. The final say is the DMV in Austin. Titles can be altered, but it is a long process if the DMV in Austin Does it. The later 235 engines that I have seen still had the distributor boss but it was blank. It would have been simple for the installer to stamp the old engine number on it. And it was the recommended practice back then. And I have first hand information because I was swapping engines in the late '50s.