I had noticed awhile back that the front disks on my 71 Elky didn't seem to be grabbing correctly,yet at the same time one of the calipers was leaking.So I figured I'd upgrade to the "Stainless Steel" dual piston kit.I installed new hoses also.I did what the instructions said for seating the pads.My front brakes still don't grab really well.When I push on the brake pedal ,it's like I can't push hard enough; which is not good when I'm driving down a short hill.If I try to powerbrake it ,before I start to let off the brake, the car is already rolling forward.I had to change the M/C a few years back and have heard about problems with the bores being oversized.What do you guys think?

do you have a power booster? if so, how many inches of vac. do you have? need a good 12-15 to run one efficiently. a big cam will have very little vac too..

If you have a booster, start the car while holding the brake pedal down. The pedal should move down 1/4" or so when the engine starts, which indicates that the booster works. If there's little or no movement, check the vacuum. As mentioned above, a hot cam will usually give you less vacuum. That could be the problem, especially when power braking. I usually lost all vacuum in my Camaro when doing burnouts, and almost had to push the pedal through the floor to make the car stop. Didn't even have a radical cam, think the specs were close to Comp Cam's 280H. Brakes worked just fine for normal driving though.

I've been running the same Isky 292 Megacam for about 7 years without a problem . I had checked the vacumn once before ,it was 11".A little low but it never presented a problem.I'll recheck it tommorow, maybe the original booster finally gave up.Could it also be the check valve that plugs into the booster?

Could be the valve or the booster. Make sure it holds vacuum after the car is shut off. 11" sounds low to me, but if it worked before...
I dont know. You might add a vacuum canister anyway...

I dont know exactly what 'stainless' brakes you have, but if the pistons on a dual floating or 4 piston opposed caliper are below 50mm diameter, you might want a 1" master on your Chevelle for a street application. If they are below 45mm, you might want a 15/16, and if they are 40mm or less, you might want a 7/8 or smaller, even if they are power disc. That's just a rough guide. Some people like a harder pedal, but those put it close to stock ratios. It also depends on caliper piston retraction what master you can safely run for volume, and what pad type and rotor size can also dictate how much pressure you need.