216,235 and 261's don't have valve seat inserts as original ,but machining in new exhaust seats is common.
It's hard to believe the piston and valve aren't mangled lumps being that the exhaust valve is angled or canted about 20 degrees and hard to believe an exhaust seat fell out and and fell back in with no drastic damage.But the exhaust valve sits in a deep pocket,so just maybe.......
Why did the valve locks fall out in the first place?Is the top spring retainer ok?
I dropped a single lock washer by accident into a V-8 intake manifold once,when the engine was started,the single washer broke a ring land on one piston then managed to migrate into 2 other cylinders leaving fresh marks on the piston crowns.Perhaps ypu have loose hardware floating around in the combustion chambers,got an aircleaner on that engine?
