air cleaners and improving air mixture on 250 six

[old cool]

So, the weekend is coming to a close and its now time to putz with my 66 GMC 250 manual. I'll try to keep it short but need some tips before I start turning screws.
Carb is new Rochester monojet. Gas mileage is so-so. (heard that's typical).
Truck burns rich and needs absolutely no pumping to start (choke closed when cold). Some bluish gray exhaust when started. Currently I have an original oil bath air cleaner. An acquaintance said a papered air filtered set up might give me a boost in air mixture which made sense. I know there's an air mixture screw but before I start trying to fix something that ain't broke, thought I toss this out there for some TA. In addition, anyone know where I can pick up one of those original wide body air cleaners for the above carb? Got to be a ton out there.