Does the carburettor have an electrically operated “anti-run-on” valve?
If so, worth checking the connections as it will have been one of the things that has been disturbed in the re-fit process.
Also, are there any lengths of rubber pipe in the fuel line? These can fail internally in such a way as to give these symptoms - a friend had this on a Midget and spent weeks looking for an electrical issue when the fault was fixed by changing a short length of pipe.
2014 4/4 Rolls Royce Garnet Red
Teddy - 17h1 Irish Draught cross