AHC: slave majority in US South

With a PoD of 1763, the US South needs to have at least 51%, desirably 66% Slave population. How can we achieve this?

I was thinking of a Haitian Slave Rebellion version in the US South. Obviously OTL had way too less African-Americans to start a rebellion. If it is two third of the population then the situation may change.
 
I do not think it would make a significant difference and there would be little chance of a slave revolt. My evidence is that most slavery was concentrated within specific areas of the US South. In these places the slaves were the majority of the population and in many cases >70%. There were no slave rebellions on the scale of the Haitian Slave revolt. Take a look at the map below to see what I mean.

https://www2.gwu.edu/~folklife/bighouse/images/iii3.jpg
 
Top