Vortec head problem?

['69 Gmc]

First off, this is my first engine build. I recently bought a set of 062 vortec heads not cracked. They have the Alex parts 110# valve seat springs on them. Not machined but will supposedly clear up to .550 lift. (I plan on running the camp xe268 .480 lift). My question is with the valve tips. All are very mushroomed/ rounded to the point where if they where ground flat the rockers would hit the retainers. What would have caused this? And would y’all recommend all new valves? I’ve almost purchased Alex parts stainless valves set a couple times, but I’d hate to put a new set in and the same thing happen.
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