Seems like I have to keep advancing my timing

[rich weyand]

It could be that you are running way lean. A leaner mixture burns slower, and needs more advance. Could you have gotten a bad load of fuel, with crap in it? Or be getting debris from the inside of old fuel lines? Rubber fuel lines age-harden and should be replaced after 15 years or so. If the Holley is internally clogged, you could be running way lean and lots of advance is getting it limping along.

The correct timing should be between 12*-16* BTDC at idle with the vacuum advance disconnected. Then connect the vacuum advance to manifold vacuum.

To get it to idle at 12*-16* BTDC, you may need to richen the mixture, to speed the burning process up. Set the timing, connect the vacuum advance, and then adjust the mixture for best running, usually to highest vacuum at idle.