Crikey, 12 quart that is a beast.
How much Beef you going to do in that?
Anyhoo, my recipes are for 15psi, but like all pressure cooker recipes
You've got to trial and error your own kit.
I've also used 13psi cookers with no notable difference in performance.
I also think theres a lot of duff info on the web about psi difference, just to sell more pots.
cheers Chewy