The motor in the Camaro is the 305 TPI (tuned port injection) 305ci, 190hp engine (RPO LB9) The 305 TBI (throttle body injection) was used in the Z-28's from 1982-1984. In 1985 Chevy came out with the famous IROC-Z, introducing the TPI system taken from the Corvette.
The compression ratio will increase when the 305 heads are put onto the 350 block. The 305 heads have smaller combustion chambers then the 350 heads. There are many factors that can change compression ratio, combustion-chamber volume, the deck height (the height of the piston above or below the block deck), the head-gasket volume, and the piston design that will either add volume (a dished piston) or subtract volume (a domed piston) from the combustion chamber.
In an article about a 305 TPI to 350 TPI swap the changes needed include:
ESC (electronic spark control) if equipped),
ECM (depending on year),
and PROM (programmable read only memory)