You said your bottom end was stock. When Chevrolet built this motor, they installed the piston with a deck height of around 0.035". That means that at top dead center of any one of the pistons, the measurement from the top (or crown) of the piston to the block deck is around 35 thousandths of an inch. When we add the head gasket thickness to that figure (I'm assuming a gasket thickness of around 0.040" (40 thousandths of an inch), we get a squish figure of around 0.075" (75 thousandths of an inch). This is the distance from the crown of the piston to the underside of the head with the piston at top dead center. This distance is too wide for the piston to be able to squish (squeeze) the mixture and shoot it across the combustion chamber. When you set the squish (also called quench).......(do a search on Google to learn more)......to around 0.035" to 0.040", you minimize the distance and get the best squish, but still just barely avoid a piston/head collision due to the stretching of the crank and rods as the piston comes to the top of the bore.

Without the "jetting" of the mixture across the chamber, you can't run a compression ratio much higher than 9.0:1 on available pump gas without the motor detonating. (sounds like shaking a tin can full of marbles). That is the sound of the motor beating itself to death and it won't last long if it is detonating. If you can visualize a sledgehammer blow to the top of the piston every time the plug fires, then you can visualize what happens when the motor is detonating.

You would want to determine what compression ratio you will run first. That will be determined by the heads, piston crown configuration, deck height and gasket thickness. Once you have determined the c.r. you want to run, you want to set the squish with the gasket thickness and deck height (distance from the crown of the piston to the flat surface of the block deck). Once you have all this figured out, then you can think about ordering the cam you want to run. You see, you can't just run out and buy the cam without knowing all these other things. The cam supports the total combination of parts. You can't make a motor faster just by throwing in a lumpy cam if you don't match the cam to the c.r. If you do, you'll have a motor with a soggy bottom end that would have run better with the stock cam.