Find a builder before waist a lot of money and time ..I Spent a year and a lot of parts and money fighting a port timing issue. Two sets of carbs two sets domes coils Cdi reeds flywheel nothing fixed my low end bog .. Now I'm going to a bigger carb and having the ports fixed.. Not saying your is port timing but unless there something wrong with the carb it self I bet you have other problems .. What jets you have in it? Are they sync ?