Going back to the engine has it got two small holes under the mag platform where rivets could have once been,still think its a spare engine batch.
below spare engine as listed in parts book,the number is similar to the steel tag engine.

Hey, Steve. Thanks, I understand. I don't think my lineup originally belonged together at all. I'd like to refurbish it based on the engine and most of the parts. The frame is made much later than the rest of the bike. That's why I was trying to track down the engine numbering.
Thanks for the information,I appreciate it.

email (option): hans.41@seznam.cz

I would agree with Steve. The Frame is what determines a vehicle. It's the part that the authorities would acquaint the vehicle to. Plus your frame is recorded and therefore much easier to determine the spec. Mine is from the next contract. By then they lost the steering damper and were fitted with the 7/8" handlebar and standardised Amal controls. Ron

PS My 741 is 1942 ex British Forces under the Lend Lease scheme.

email (option): ronpier@talk21.com

Thank you both. I'll build it with C 5423699. Thanks again for all your help.
and, military bikes forever...

email (option): hans.41@seznam.cz