Ted, a guy on .org is getting his best mpg with a 57 jet. if i were you i would start with a 55 and see what happens. just keep jetting down 2 at a time till it surges.
i would buy 55's and 53's to start. if the 55 dosn't surge try the 53's...
also back off the accel pump, you will see the control arm on the valve cover side of the carbs, move the linkage to the lowest hole, that will back off the pump shot.
