[HardcoreZ28]

Sounds like a good enough excuse to swap out the 305 to me. As far as what will and won't pass it's touch and go. I originally had a 305 TPI and now I'm running a 383 with Super Ram, 219 cam, AFR heads etc. There's a lot of debate on emissions, but I can tell you that any good engine will pass emissions if all the pollution devices are still on it. The goal of performance engines is to make power, and the best way to make the most power is by being as efficient as possible (in a street car). With efficiency comes clean emissions. So you can cam the hell out of a car and feed it tons of fuel and air and as long as it burns all that fuel while making power, you'll burn clean.