I need to find out the minimum and max line presure I should have when I step on the brakes so that I know what scale of a guage to order in.
Thanks.

i'm not sure of the brake pedal lever ratio for the chevelle, i can give you an example for the 1st generation camaro with power brakes (which is probably the same).

the brake pedal lever ratio is 3.8:1, master cyl piston dia 1.125", with an 8" dia power booster and an engine making 15 inHG of vacuum, and the driver applies 10lbs of force to the brake pedal.

the combination above would yield around 411psi from the master cylinder.

if you don't have power brakes, everything changes. the pedal ratio changes to 6.25:1, the master cyl piston is around 1" dia. now if the driver applies 50lbs of force to the brake pedal, you're looking at around 398psi from the master cylinder.

maybe the above examples will provide you with enough information to provide some kind of baseline. calculations and real world don't always match up, so be carefull when working with brakes.

I'm not clear what your asking here. Are you installing a brake pressure gauge? If that's what your referring to my auto meter is 0-2000 psi. With my hydroboost I can take it past the 2000 psi mark with minimal pedal effort. Brad.

Just want to check and see what each wheel is seeing PSI wise as a means of checking for faulty hoses or master cylinder issues.
Thanks.

Here's a set
http://www.thetoolwarehouse.net/shop/WAE-BEQ0397.html
just something to compare with.