B&M External balance flex plate would allow using 318 converter (or other neutral balance converter.) Has stock size 5/16" bolt hole pattern for both big and small converter bolt patterns, and the large 7/16" bolt holes for aftermarket performance converters.
https://www.holley.com/products/drivetrain/flexplates/b_and_m_flexplates/chrysler/parts/10236CR13 converter has the two small weights, 1600-1800 stall.
CR15H converter has the triangle weight, listed as High Stall (I think 2200?)
Trans Star Converter catalog:
https://www.transtar1.com/TranstarI...verter%20Catalog/mobile/index.html#p=665
