That's a 1955 or newer car engine, or one from a 55 second series or newer truck. The solenoid-type starter and the low mount water pump is a good indicator. Post the stamped letter/number sequence beside the distributor to allow the number crunchers to give you an exact year and application for it. You'll need to use the original intake, exhaust and carburetor for your cabover, and an adapter to use the high mounted water pump. The front motor mount will probably need some adapting, as well.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!