Titanium spring retainers

Fun fact I purchased a 1969 340 that was built in Honolulu speed shop and built to race at the local drag strip. It came back from the islands with a navy soldier who had more money than interest in the sport I purchased the whole 340 swinger for $500 in 1980 with a converter problem and the owner just wanted to bail on it. There's a lot more to the story but where I'm going is it had brand new crane doubles valve springs and aluminum retainers even with factory valve rocker arm assemblies that motor seem to have an unlimited RPM I always contributed part of that to those ridiculously light retainers.