Engine change done by Porsche on early 911s (series ## thread)

Fellas,

I am looking into buying a 74 Carrera MFI, you know the deal, 2.7 liter, 210hp etc. (European car in Europe)

The thing is, the engine was replaced by a correct type engine (2.7 MFI 210hp), and the seller says it has a KD stamp on it which proves it was done by a Porsche dealer, as in "a official motor change", likely at early stages of its life. As far as I know KD stamps for engine changes done by Porsche were a common thing for 356s and if I am not mistaken it also can be found on a CoA (?) in the case of a 356. I have no idea if early 911s (we are talking about a 1974 car) had that also? Can someone enlight me here?

Thanks for your help!