Some tips:
Try bumpin the idle to at least 900 to 1000. IMO, most 6 packs like the higher idle.
Get yourself an idle solenoid so it will shut off when you want it.

Run a fuel regulator with gage, set for about 6.5 psi esp if you have the larger needles and seats.
Run the fuel level so it drips out the bottom of the site hole.

BTW, you running a vacuum advance? You set the idle and timing without it connected?

Dallas