Honda CB750 K

[iscqda]

I have a 1975 K registered CB750  -   The engine is and came dismantled with the engine number on casing starting with 278.... which looking at J Wyatt's book indicates it is off a K7 - it is not an import -   Ideally i would like to put an earlier engine in which will be in keeping with frame .   Does anyone know if engine is same or parts from later engine  will fit earlier engine-  ie are parts interchangeable?

Also, I have an original genuine Honda 4 into 4 which is off i understand a later K8 model,   three of the pipes are superb - one has a slight graze -  i think someone must have come off the bike and probably never used it -  I bought as i thought they might fit my earlier model but there are differences -   Would anyone be interested in a swap?

[Nurse Julie]

Is your bike a UK model frame and engine or is it an import? A K registration wouldn't be a 1975.
Oops just noticed you said not an import. But it can't be a K7 if registered in 1975, we were still on K2 heading towards launch of K6 at that time. 🤔🤔🤔
If its a UK model, the engine numbers don't tally, as we never had K3, 4 or 5 in UK but the engine serial numbers kept running concurrent.

[iscqda]

Frame and log book  is K2 (1975)       - the engine is much later and yes is uk model