I bought my 04 Aveo with a bad timing belt (plastic pully failed) ... I pulled the head... had the machine shop replace the bent valves, complete valve job and resurface... New belt, pullies, seals, water pump.... that was about 7 years ago. Doesn't burn a drop of oil and passes smog every time. No reason to replace the engine with one of unknown health.. especially if your old one was quiet and didn't use oil. The valve stems are so small... they bend super easy...so even though all pistons had some dings...it doesn't hurt in any way... (I'm a 40+ yr mechanic)