[~The Jester~]

I bent a total of 17 valves, and 12 pushrods last season, for various reasons. Most of them went when my timing chain went south. Other reasons are misadjusted rockers, CHEAP pushrods (I did that one too), over revving, weak valve springs, weak lifters (hyd), worn/broken valve guides, etc etc

Considering your circumstances, being on only 1 valve, I'd suspect misadjusted valve lash. An overrev usually bends prods on more than 1 cylinder.

Do a compression check on #5 NOW, check and make sure the valves themselves aren't bent as well. You might be yanking the heads. I've gotten lucky a few times and got away with just replacing prods, lets hope that's the case here.