I sorta agree, but on accel, vac advance should move up quite noticeably. Set the base timing around 8 degrees, go from there. Drive it hard, should not ping if an automatic, WILL ping lightly if a stick and lugged down a little. If you have loud exhaust, you wont hear it ping.
Oh yeah, GM HEI always gum up inside, especially after sitting. remove rotor, clean and WD-40 weights, make sure they move and return fully smoothly. Check that plate rotates under vac advance.
