Well I am not sure there is a way. See the frame and engine numbers do not match so you cant go by either one of those. I would guess that if honda put anything on for special numbering, it would be on the neck somewhere.
The ride IS the adventure. The destination is just to get gas!
I would check a copy of the Haynes manual for the DOHC 750 bikes. If I had mine with me I'd check it for you, but my mechanic is using it to put my broken bike back together. In the section for 81-82 bikes, they list serial number groupings for the different models of bike.
If no one thinks it's a copyright infringement to put that info up here, next time I get my manual I'll upload the info.
Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.