C4 vs C5/C6 based subframe question

[Rhino]

I'm currently in the early planning stages of building a front subframe for my '68 Camaro. In my possession I have the arms and spindles from an '84 C4. I was originally planning on using them, although everybody mentions how the C5 is a technologically superior platform to start with. Unfortunately no one is ever able to back this up with solid reasoning as to why. Searching back through previous threads, I found it to be very common to use a C4 setup up to 2 years ago.

Finding a full set of used C5 components appears to cost between $500-$700. For a car that will be about 80% street use (spirited driving), 10% Drag, and 10% AutoX will I be able to notice a large enough difference to justify the increased cost?

I realize that the C5 components are technically superior, although can someone provide me with numbers as to exactly why they are a better fit when retrofitting into a musclecar? I'd like to do some number crunching myself, although I have not yet been able to locate a C5 for measurements/comparison.