Anyone here make their own (tacos) al pastor?

I bought a Sear'd vertical skewer because it was 1/2 off and I love al pastor so I want to try making my own. I know I can buy the pre-cut and pre-marinated meat at places like La Michoacana but I also read meat markets will use close-to-expiring meat to marinade.

I'm wondering if any of y'all had luck buying your pork at HEB/Kroger and had them slice it thin for you? Also, do you just do a shoulder or add other cuts?