If the engine is stock, first check the point gap with a feeler guage with the rubbing block that is on the points sitting on one of the 8 high points on the dist shaft. Its better to use a dwell meter if you have one. (dwell is usually 30 to 32 degrees, point gap is usually .017)
After checking/setting the points, THEN check the timing. Using a vacuum guage leaves too much room for error in my opinion. Find the specs (most Ford V8's are 6 degrees) and un-plug the advance and set the timing with a timing light. Re-attach vacuum hose and set the idle speed according to specs. (usually 600 in drive)
As far as the popping noise, its pretty much how it goes with glass packs. You can usually mellow it down some by having a muffler shop put in a crossover pipe between exhaust pipes as close to the engine as possible.