Thanks for the assistance Harry and LRCounty. Using a combination of pulling the cable right out (it's well labelled with this conversion, LRCounty) and flicking the fuel pump on and off I can get it to almost behave itself, but every time the pump is left on, the engine floods. So I'm guessing that the main problem is the floats. I'll wait a bit to see if using petrol frees them up (as you were suggesting happens with Ralph, Harry) otherwise I guess I'll have a crash course in carbies ahead of me. I can get it to start with petrol now, by only running the fuel pump for a short while before turning it off and starting. So at least I'll be able to get it to a petrol station for gas when the time comes.

Thanks again for the help - if/when it all works 100% I'll post and let you know.