I was thinking about your return line build.
I've owned a few Eldos (472, 500, 425) and the version of the fuel pumps had the three line set up. Third one being for the return fuel so fabrication wasn't necessary off the carb.
I was thinking that the fuel filters available for Fords and Chryslers that had the restricted fuel return line built in the to help clean up the fuel line fabrication for you Caddy set up.
Just my .02 cents worth.