Although I've not heard or seen the vehicle myself, I understand it runs smoothly on the original Carter. The problem was that you had to have a permanent hose connection to the gas station otherwise the tank emptied before the next station. With the Webber, there is some uneveness on the first choke but it is driveable. when the second choke opens, there are clouds of black smoke and it drives as if a manual choke is out - hesitant, little power, relucant to rev.
Thinking about your comment on the ignition, is the Carter much more tolerant of ignition weaknesses than the Webber ?