For your application with a slanty, the Chrysler 3 +1 is ,IMO,a terrible option. You will need as many gears as possible.I vote close ratio-non O/D-5speed for a NA slanty.
But if you are going to turbo that baby, then it might work, but it would need specialized tuning. And when you forget it's a 3 + 1, your turbo will blow up that O/D gear.