just swap the head for another, pistons are unlikely to have been seriously damaged by this, if so you would have to replace entire block anyway so either way it all good.
pretty sure all base 2.0 8v heads are same, but etka is confusing on this issue. looking at it, its only camshaft and thickness of valves thats diffo? i.e. as long as you get a complete head you're ok. not 100% sure on that, cant really make sence of what etka is telling me