[Blackbirdws6]

You've used your engine in more ways than most so just time for the refresh and could have dropped a valve which would have been more of a disaster. Possible the springs got tired, valve float and depending on your piston to valve clearance, maybe they kissed which bent the valve to get it stuck in the bore. Get the best springs you can, clean it up and send it. Understanding you aren't trying to snowball the build but can you go with a bigger set of header primaries without too much trouble?