I have the exact same setup on my '87 60. I went with 12.50s, and they give it a really good stance from the front, I have the Yokohama Geolander A/T +II, they are really quiet, and clean themselves real well, good traction on ice, mud, rock, and onroad, you can get them from tire rack for a little over 100 bucks a pop, got my set delivered to my house for well under $500, and mounted them on 15x10's from JT. I like the tread design, and not many people have them, every other truck has BFGs.
just my $.02
just my $.02