Well, caster.. camber and toe values are not fixed in concrete. Bias ply tires that came on these cars ran better with different settings than newer tires. Those are flexible numbers and they all interact. Excessive toe in or out will scrub tires off quickly. Caster will effect steering centering and ride stability. Camber effects your ability to push the car through the turns at the minor expense of tire wear.

If you have stock upper control arms, you are somewhat limited to your adjustment range for these settings. You won't be able to set the extra caster that improves stability. Some aftermarket UCA units permit you to set more caster and camber which improves high speed stability and cornering.

If you're not going to set this up yourself, you should ask some tough questions from your alignment shop. Many shops "set the toe and let it go". Many times, shops have turned the keys back with the excuse "doesn't matter" or the beat up old car can't be set up. With the shim pack at the UCA to set the Firebird up, many shops just won't be bothered. Plenty of shops don't even have the shims required for set-up on hand. Most diddle this or that based on what the computer tells them and they have little clue what effects what. And they have fifteen minutes to spend your $50 bucks.

Start off by describing what you expect in the way of results. Many shops will tell you they don't have the time or are "not equipped" (experienced with these older cars). Some shops will start off saying it's extra cost or they can't do it. Many start of by saying that parts you just replaced are "worn out".

I recommend buying the tools, learning about steering angles and their effects on handling, and doing this yourself at home. Setting toe and letting it go is easily done in your driveway with some wood scraps to make a trammel, a tape rule and an hour of your time.