[LS short box]

On my 68 C10 and other hot rods I have used C5 Corvette front discs and 2002 Camaro rear discs with great results.
I sourced the C5 brackets from Custom Works a vendor on this forum. 13" discs.
The Camaro rear discs are 12". Built in e-brake.
That's combo I'm running on my current 80 Camaro project. Yes you need 18" wheels.
But on my 68 I was running 20" wheels so the 13" rotors looked a bit small. So after some investigation I found out that the C5 ZO6 front discs are 14"but still use the standard C5 caliper. I made new caliper brackets spacing calipers out 1/2". They bolted right up.
The plus part about using the C5/Camaro stuff is replacement parts are only as far away as the local parts store.
Having said the above my go to guy for brake advice is Tobin at Kore3.com.
Pic of the 14" C5/Z06 front brakes.