The rotors come drilled with the bolt pattern of the hubs, so 'Vette rotors are drilled for 5x4.75, any other bolt pattern requires the center to be drilled for the new bolt pattern. I suppose you wouldn't need to redrill if it's a 2 piece modular rotor, though when I looked at those for my application they were triple the price, again new hubs would be cheaper. Kore3 did custom milled hubs for me for way less than a set of 2 piece rotors with caps, bearings and seals and anodized. Not to say my brakes were cheap they weren't not by any measure, but they are cheap to maintain, for 13.5"F/13"R brakes and have integrated parking drums.
These are the type rotors I have, DBA T3 one piece:
Either side slotted, no holes.