Wanting to convert for safety and reliability to disc.  Having a hard time finding C-body conversion kits, but have found many A, B, and E kits.  

My question:

If it works for a 1968 A, B, or E...will it work on my C body?  

Can I swap spindles and brake components with a Road Runner, Belvedere, or even Coronet, Newport, or 'Cuda?

As far as I'm aware, the only real difference in a C body is a few inches more on it's chasis.  

kits I've found are below, but I don't know how well any of them are yet.

Just Suspension

Stainless Steel Brakes

ECI *ecihotrodbrakes.com*  

Best bet for a C body car is to put some 1973 C body disc brake knuckles on there.

If you really want aftermarket brakes then you'll have to search a bit.  AR Engineering makes a 13 inch kit for C body cars but you'll need to run 17 inch rims to clear.