Well then if you have a large enough sample for positional stats to converge then you also will know if they do anything funky like limp-reraise AA/KK. So let's also assume he's straightforward in this respect.
So here's what the simple subtraction gives us
However at my typical stakes a villain is more likely to have the small pp's and more sc's in his range so I would adjust it to look more like this
Again - I'm no genius, it's just how I currently do it...