How about "STOLEN REPRODUCTION"? This would be appropriate.
It looks like the info I have suggests that the 763 motor is the replacement for the 733, I am presently assuming that both are 300v parallel mount, and self ventilating.
I am not too sure yet about the 761. I have found one picture of a truck for a std. gauge engine. It looks like a 600v, parallel mount through a double reduction gearcase and force ventilated. Either there is a version of it that is "wheelbarrow" (axle) mount narrow enough for 36" gauge or I have the wrong model.
Sometimes those model suffixes just mean an updated model, other times it is something for a substantially different application.