Well black plugs would mean rich but popping through the carb usual means lean. I would look at what you have done so far. You say it ran good before you pulled the carb and distributor.
1 Check the wires, it is real easy to mess up 5 and 7.
2 Did you use a new base gasket when you reinstalled the carb, if not
3 if you are running a stock cam your vacuum is to low, I would expect
around 18 at idle. Try spraying some wd40 or carb cleaner around the base
of the carb to see if it changes the idle. If it does you have a vacuum leak.
This could cause the power valve to open early and soot up the plugs.
The vacuum gauge is telling you something is wrong, usually low vacuum is either late timing or a leak. Did you have to adjust the valves. A tight valve can also cause popping through the carb. My bet is you have a vacuum leak. let us know what you find