Austin, I know how you feel, my WRX has had spongy brakes from day one, brand new, and it's the only thing that deducts from driver confidence in that car. I think it's the norm for Subaru brakes, aside from the STI which is very firm. My Z setup is the 15/16" ZX MC, original 280Z booster, all the factory safety&prop valves, stainless/teflon flex lines, AZC brake kit, and I have an extremely firm pedal that works right off the brake light switch. They bled easily with no hassles. I actually had to ease off on the linkage to get the brake down low enough to do heel and toe comfortably. Something is wrong with yours so don't think it's inherent. I am not familiar with the vette calipers. Check for firewall flex, out-of round rotors that push the pads back, and maybe mess with the safety and proportioning valves if you still have them in the lines. They could be holding air, dirty, or part clogged.
I HATE spongy brakes as well. Pet Peeve.
One of my recurring nightmares (yes I have dreams about it) is a spongy pedal with little or no brakes...probably from when I boiled the fluids in the stock system at Limerock Park.