"13's" or "13.0"
13.90's are one thing, but if you want "13.0" you might as well aim for 12.90's. and that extra second is gonna be tougher.

That said - a k1500 is a big bitch. I'd build an lq4 (or lq9 if you find a good deal on one) and spend the savings on gearing the hell out of that thing.

Big cam, heads, intake mani, tb, headers, veeeery free exhaust and some dyno time with a good tuner.
Even then I'd keep a bottle of "the dentist special" on hand... knowwutimsayin

Oh - and go ahead and start saving to rebuild that 4l60e if you're auto.