Working my way through fuel system on the 80 Z.....have replaced fuel filter in the quadrajet inlet...is there another inline filter in the system?

 

Not that I know of, but who knows what someone may have added. I'd check the routing of the fuel line to visually inpect for another filter.
BTW, that sintered bronze filter in the inlet is a POS. They plug up easily, and most people remove them and install an easily serviced inline somewhere close to the engine.

 

Your Q-Jet should have a longer fuel inlet horn, which uses a paper filament filter, and is a bit longer than the bronze filters that were used in the older flush mount inlet model. That should be sufficient, unless you're ramping up your fuel requirements. If needed, you can use a better in-line filter, but then throw the in-carb filter in the trash.