Need some advice on slicks for my '67 Notch

I would ask that instead of the largest I would ask what are the smallest that you can put on and it work properly. I would look at a 26 or 28X8 on an 8" wheel. What size tires are on the car now? If the car has a 26" tire onit I would stick with it. Plenty of cars going fast on small tires.. My old race car i ran on 6" slicks and would run 7.20 in the 1/8th.