I searched around for a while, and it seems a lot of people use ferrea valves and springs, but then use the crower retainers. Is there some sort of clearance issue I should be worried about on an h22 with custom crower (stg1 idle lobe and stg2 vtec lobe) cams?

What's with the shorter installed height on the crower 87093D retainers? "...w/ shorter inst ht (+.060" inst ht) "
Ferrea retainers the same way?