My input is that the C4 brakes are not adequate - go straight into at least C5 class or better with aggressive pads (they're going to dust just by looking at them, but they will stop). C4 brakes ran a 7/8" bore MC with power assist and
still left an awful lot to be desired. Running them on a manual brake scenario with a 7/8" bore MC is like yanking the vacuum hose off of a C4 Vette vacuum brake booster and hoping to stop (though you will have a slightly better mechanical brake pedal ratio with your C3 as I see it is a factory manual brake car in your build pics).
If you do everything "right" and still don't like how your brakes feel, we have an exceptionally powerful highly engineered direct fit conversion package available that provides a 100% true bolt in straight into your factory manual brake car:
http://www.hydratechbraking.com/C3Co...920161312A1BD0
We had a customer recently get back to us after installing his model 3007 system into his Vette, reporting back that it stops better than his CTS-V and his sport bike.
I say get with Tobin at Kore3 either way to get into at least C5 class items at the wheels. You could then evaluate how you like the pedal feel in manual brake mode, knowing that you could install one of our manual to power brake conversion systems in place at any point if you wanted to supercharge your brakes from there on in.
Kore3 is also a Hydratech dealer by the way.