Can you use stock rockers with aftermarket aluminum heads?

No you can't use OEM stamped rockers on your aluminium heads, it would ruin your reputation if anyone finds out!
But if you do use them, never EVER tell anyone.
Otherwise it's OK as long as you don't use a camshaft lift or spring load that's out of range of the OEM stamped rockers. The rockers will do their job on a couple of aluminium heads as well as they do on iron heads.