What did GM use for a fuel filter in a 67-69 Z/28? (Or any motor with a Holley) I assume it to be the sintered bronze filter at each fuel bowl inlet. Do you find these to be adequate? Thanks!

For the majority of the cars it was just the sintered-bronze inlet filter int he carb. inlet - it stops the medium to large rocks :D
Some of the Rochester equiped engines in 1969 did use a stand-alone AC-Delco GF-432 Fuel Filter, with a small return line back to the tank, installed in the fuel lines between the pump and the carb.