i just purchased a 1991 pontiac firebird with a E305 TBI motor. my question is : how difficult is it to up grade to a 383 and still be emissions legal ?? if too expensive what options do i have to pep up this 305.  

Everything from the 305 will swap onto the zz383, including the emissions equipment. You'll need to get the throttle body from a '92-'95 350 truck to handle the extra displacement. You might want to get some throttle body upgrade parts from www.turbocity.com, or buy one of their complete TBI units that are built for 383 use.

The only other thing you'll need to do is get a 350 flexplate to mate the 383 to the torque converter, and a chip for the computer to tune it for the 383, which can be had from Superchips or Hypertech for a small price.

I'm doing something similar with a '92 305 RS Camaro, but I'm using what's essentially the 400 HP Circle Track crate engine.  

thanks for the info. and keep me posted on ur project.