What a lovely set! I like the look of it, and the fact it's full of mad fiddlings sounds even better. I'd definitely take it on, I love a project that's miles outside my comfort zone!
Oliver
Edit: Given the set came from Cambridgeshire, and seems to have a Pye whiff about the modifications, which clearly needed more-than-usual technical know how, maybe it was a Pye employee that modified it.. They would surely have considerable faith in the EF50..