what's the favorite replacment starter for these sixes?

You know my take on mini starters. I have not found one that didn't fit yet. Love 'em even on a big block. You'll lose the old Chrysler Waaa-waaa-waaa for the new t-t-t-t-t-t-t cause its cranking about 3X faster and using half the amps at <1/2 the weight.
You can downsize the battery too for even more weight(and cost) savings once you go mini. I went to the smallest car battery at Costco without a problem