[hound dog]

If the pistons you're now using clear the valves, and you're using the same camshaft, and the existing heads have the same valve diameter as the new ones, you should be OK. However, if your existing heads are using 1.94 intake valves for instance and you put on the AFR's with the 2.02's or the 2.08's you will probably need to flycut the pistons to allow for the larger valve O.D. and not the cam lift. But use a little bit of clay on the top of the piston, put the cylinder head on and turn the crankshaft 720 degrees by hand and see if you have any clearance. If you feel any resistance stop immediately. Use the clearances that Jack21 gave you and you should be OK.
h dog