Mpg 318

Run more initial advance. With the vacuum advance disconnected and line plugged. Try to advance it until it starts to be difficult to start. Then back off 4*'s. With the vacuum advance now hooked up, you want a max of 52*'s total. If you can not adjust the vacuum timing with a 3/32 Allen wrench located in the vacuum advance canister, back total down to 52*'s.

Re tune the carb as best you can. I myself can not stand Autolite plugs and only run the Champions in my MoPars.
What gears and tires are you running?

Is this engine a 318 or a 5.2? There NOT the same.