You're going to want to check the runout in the new rotors and don't rely on using the lug nuts to hold it on. the runout will change everytime you replace the wheel. Tap the rvet holes 3/8-24 and use flat heads to bolt the rotors on. Then you can check the runout and shim to get it under .002"
If you use the lug nuts only as many do the runout will change as the bolts are torqued. I measured this a few times and depending on the particular rotor/spindle will change a few thousands or more. Since you want to dial these in to under .002 that approach just isn't a good option. Like I said I see it all the time but it comes down to how you want your car to be.
If you visit the other vette forums I use the same handle and there are more posts with pictures there.
Here is a front rotor I dialed in with bolted on rotors.
The aftermarket rotors with slots and holes usually don't have the rivet holes in them. I have set them up as well and was faced with either dialing them in with the lug nuts or machining a bolt hole pattern in them. The required amount of time to do the holes wasn't worth it so they were dialed in to .000-.002 but I know this runout changes with every wheel change. I measured up to .005 change using lug nuts alone but it does vary with every job. Check yours and see if it changes much as you tighen the rotor and then loosen and re-torque.
The rotors were riveted for a good reason all those years ago.
Thanks all. Gary-I know what you mean about the time and trouble to machine bolt holes in them. It would be really time consuming! I'll run the car for a while (as soon as I get the chance, I'll finish it someday) and check the runout again. If it changes drastically, I'll take the time and machine the holes. Till then I'll hope for the best. Art