Battery CCA?

This website claims the Ah to CCA conversion for AGM ratio is higher than for traditional batteries.
In other words to get the equivalent of a 48 A-h Group 24, will be around 336 CCA minimum, but in an AGM we would want at least 384 CCA and maybe as much as 456 CCA.
https://www.global-batteries.com/how-to-convert-amp-hours-to-cca-a-comprehensive-guide/From the shop manuals it looks like the higher compression engines got optional 56 and 70 Amp-hr batteries in '68 and '69.