Have heard in the the past of French sandcast vins greater than E7414, but this is the 1st pic APPEARING to substantiate such.
Engine number/letter stamps appear authentic on sandcast cases. And, the frame/engine numbers of 101460/E1014143 are in the range one would expect.
Following is translation of the ad:
HONDA 750 K0 SANDCAST MODEL 1969 EXCEPTIONAL HONDA 750 OF 20 000 Km ORIGIN. _ N° OF FRAMEWORK: 101 4060 _ N° OF ENGINE: 101 4143 Arrival in FRANCE in February 1970. This motor bike at summer photographed on page 4 of the book of BRETON ERIC heading "CB 750" with editions LARIVIERE Except the 4 pots of echappements and a top of saddle, this motor bike is in its state of origin without any restoration. Only 3 owners. The photographs of details, prove the hautenticity of the modéle "K0 SANDCAST" of 1969: engine moulded with sand, keeps mud, meters, tank, exct.... cabochons of the indicators are also of the year 1969. Aprés 38 years this modéle is single, taking into account the state and of little "GUARANTEED" mileage. for all information such: 06 20 44 11 42.