sunkin valves, worn cam ?

[ripped again]

yes my exhaust valves sunk about a 1/4 inch on 6 of them, yes i ran it to the limit, did this trash my cam and lifters? 15,000 miles on cam, This was a complete rebuild except for putting hardened exhaust seats in the heads, i got about 10,000 miles before the exhaust valves started going, im putting new heads on, do i dare chance the cam and lifters after what they have been thru ?