inline fuel filters

[old cool]

I'm still attempting to smooth out my 250 inline engine when sitting at a light; in gear; clutch in; idling at 550 to 650 rpm. I realize from previous posts this slight vibration could be accelerator pump issues, plug wire, plug, float adjustment, etc. My questions today are about fuel filters. Between the fuel pump and carb, the PO installed a 3" GM or Delco type canister filter (within a few inches of the pump). There is also the original stone filter in the carb itself. Is it a good idea to have two filters? And here's the dumber question, is the stone filter positioned with the cone facing the fuel source or carb? When I first got the truck, I removed it without paying attention to position but logically faced cone toward fuel source.
NOTE: when testing the stone filter, I blew through it both directions. The air moved more freely when blowing into cone side; more restricted when I blew through the flatter side. Should there have been any restriction regardless of which side you blow through?