Welcome to the bolt page!
In 1935, the correct engine for a Chevy would have been a 207. Since it is not original as you said, you have an interesting challenge. It is a straight 6? Looking at the resources available through this site, it appears that anything with a 373 prefix would indicate a 50's 235. I believe the 'N' at the front would indicate a 54 block, but the casting number doesn't match up.
Any other thoughts?
