In Washington its possible to change the number on the title to that of the body just so you can change motors. Arizona probably has a similar process.
Based on your planned usage I'll stick with what I already said. A '54 truck 235 is an easier swap than a later 235 because it has the shorter water pump and will better fit the space.
You haven't said what the vehicle is. If I remember correctly the 207 uses a different bellhousing, which in turn matches different transmissions, than that a 216 or 235. Its a significant job, but swapping any motor into the place a 207 came out of will be a big job.
