5.9 Weighted Flexplate

I pulled the 5.9 out of my wrecked '94 ram and plan on using it in my '70 dart. I was looking at the flex plate and it's a neutral balance while the convertor on the 518 trans is weighted. I've replaced that transmission several times over the years from hot-rodding the truck around. I've bought the weighted convertor by simply giving the year make and model of truck.

Since I plan on using a 727, I'll need a weighted flexplate. Which years used them? And are the aftermarket ones any good?