it would prob be cheaper with rebuild but you may want to uprade? maybe your fuel pump is going or clogged lines/filter?

 

+ 1 on the filter. Q jets can be very good carbs if the right person lays hands on it. Other wise the good ole 600 holley is a good alternative. I would change plugs and wires. Cap and rotor. Fix any vacuum hoses that look dry and crusty. Check them for leaks. Its hard to make anything run good plugs. How many miles are on it? If it has a ton of hard miles on it the cam may have worn lobes.