I am looking at running a 19x9.5 square setup. What offset should I have these built to and what would the recommend tire size be?

 

Not a lot of folks run a 9.5 square setup, but i believe there are some on the Wheels thread.
Depending what your options are for offset, a +40 or higher (up to +45).
Tire size, 255/30/19 if you're going square.
Typically a 265/30/19 would be used on the rear, but I have a feeling it will be too big for the front, so downsizing to the 255/30/19 is your best bet.
I think at full lock you will likely still rub on the front due to the 9.5 no matter the tire size...but that's at full lock.

Your best to check the Wheel thread and see if anyone has 9.5 in the front.