318 Gas mileage?

I think you should be getting more MPG's. The cam isn't to large. I'm not a fan of that intake though. I'd perfurr a Performer myself, but that's netier here or there right now is it?

Try moving the intal to 15* and limit the total advance to 32*'s.
How's the plugs? Black?

Mileage getters are;

Headers, but they suck on the first bump, but still help.
Your dual exhaust should be 2-1/4. An H or X pipe would help and muffler choice isn't so critical.
And MSD or equal like the Mallory 6 box or Summit racings multi spark box.
Wide plug ga. You could go to .050.
How tall are your tires?

Oh, my 318 with a Crane 216/228-.454/.480 with headers w/2-1/2 jegs exhaust, LD4B, Carter 625, MP resto unsilenced air cleaner, and a orange box fired ignition is getting 17 - 18 Hwy, 13ish around town.
3.21 gears w/225/70/14 tires. And a 904 lock up tranny.