1972 dart 360 with 904

So only option is new styles flex plate ( yes I know notch is cut out ) and a zero balanced converter . Got it

secondly what diameter ? I see so many 10",11" and others diameters listed for a904s . They need teeth on them as well and many pictures shown don't have teeth on them .
Not the only option, but it's what I would call the better option. The other option is a 360 only weighted balancer and a stock flex plate. Thing is, both options cost about the same, so why not go with the better flex plate?