Z. Ray, Jim Inglese sells what he calls debris screens that are really good and not restrictive as the ones you show. I have my GT350 and run 48 IDA Webers as well. As for your original question re advance. 38 degrees total all in by 2500 rpm, I had my OEM Hipo distributor re-curved with 29 degrees in it by 2500' 9 at the dampener.
~E