How much lift on a camshaft can I get away with before possible damage occurs to the valves from the piston?

Depends on the pistons and whether the crank is stock and the head. Alot of physical measuring.

Put number one at top dead center (I like using a long screwdriver in the spark plug hole as a feeler), if you know your way around engines, take the keepers off the exhaust valve (if a valve is going to go into a piston, it's the exhaust valve you worry about), and lower the valve down until it is sitting on top of the piston. Now you know how far it can go. Now just do the math. 3/4 is always safe, but I take it you want to go full race. If everything's stock, it should clear, but you'll want to research the recommended pistons to be used with the cam you choose. If forged pistons or pistons of a particular dimension are recommended, don't be penny wise and pound foolish. In either case, you'll want to eliminate all valve float anyway.

Stiffer springs helps keep the valves from floating. Be cool if desmo cams & followers were available for Chevys . . . oh well, can't have everything.

by the way, if you don't know what you're doing, don't take the keepers off a valve unless you know that's an engine you can reassemble the spring & keepers without removing the head. It's a real ***** getting it back together.

It depends on the pistons, valve diameters and head planing. The duration also comes into play because it holds the valves open longer. With flat tops or dish pistons up to a 292dur/540 lift cam will be safe.