Valve keepers cracking

[flthd31]

Hi guys, I'm currently tearing down a 59ab and ran into something I hadn't seen before. 6 of the keepers (3 piece style) are cracked and broken as seen in the pic. This engine has been reworked in the past as it has late model valves with one piece guides and adjustable lifters. Valve lash look OK before tear-down.
It has stock 3 3/16 bore, 3 3/4 stroke and all the valves came out fairly easily and look to be usable except for the bad keepers. I have bags full of keepers from other tear-downs for replacements but not sure if I should use them or go to the 2 piece keepers.
The only thing odd about the engine is that it had a truck head on one side and a car head on the other. Could the difference in compression ratio have caused this? Any other ideas?