70 340 block/ 73 crank and balancer

I have been looking for pullies to work on my 70 340 Ac car. I have had no luck. I found out my harmonic balancer and crank may be a 73 cast crank. I put a 2500 stall convertor in the car but has no weights on it. I'm guessing it's not balanced. I have drove the car and haven't really notice any vibration. Do you think I will have to change the stall? Does anybody know where I can get a 73 340 crank and water pump pully? Apparently they are different with that year.