Rear end advice for racing with a 4 speed

your car is 100% mopar? :realcrazy:
Some are, some aren't. ( and I've got two narrowed nine inch with spools)
One is a French designed German built Buick with a Chevy motor and a Ford rear end, so I dont consider myself a purist....... but all six of my mopars have all Mopar drivetrains. (Including three flatheads).