Texas Shadow

Running a totally stock '98 LS1 except it has K&N intake, true 2 1/2" duals, shorty headers, and ECU reflashed to 2001/2 parameters. I'm considering a head/camshaft change along with a Z06 intake manifold. I know this subject has been beaten to death from doing some searches but I'm trying to find a good combination that will give better power but not screw up drivability or fuel economy. The car is a daily driver that is currently averaging 19.5-20 MPG back & forth to work. It dyno'd about 18 months ago at 311 WHP. I'm a total noob when it comes to the LS1 so need some experienced folks to weigh in.
Thanks.