This is a long shot, but I have the registration for a 741B, number GDA-2823, from the year 1950-51. To clarify, this registration slip says model 741B, serial number GDA-2823, it does not list the year of manufacture, and this is the registration slip only from the year 1950-'51. (I'm not certain that's a 741 serial number... but that's what the registration says.)
Send me a photo of the number on your engine and I'll send this registration to you!741registration.jpg
Send me a photo of the number on your engine and I'll send this registration to you!741registration.jpg