I found a little more info for you, on the correct counter weight, in this thread... https://board.moparts.org/ubbthread...24811/magnum-360-flexplate-solution.html

"I based all my numbers on mopar spec. LA engines require 19.79 in.oz. Magnums 14.65 in.oz. of weight offset.

Also, am relying on the 1/8 inch thickness of B&M steel being fairly consistent.

BTW, steel = 4.537 oz/cubic inch"