No Idea when 'KVA' started to be used rather than Watts for AC power, but I presume the need to account for power factor would have arisen quite early on. But it as that frequency together with the assumed date (based on production of B&S engines) which lead me to think of a spark TX for which
800 Hz applied through a step up transformer (jigger in early Marconi parlance) would be just right.Just to dig myself even deeper, I have been trawling the web for info. See:-
And
(Now was that last one a naughty hot link?)
Mike, when you get the engine and are sure of all the details of ID plates etc, I could put a request for information in the British Vintage Wireless Society bulletin if you like.