Your vacuum advance is working properly.
You even have it connected to the proper port on the carb.
The correct port is called ported vacuum, which means the port is above the throttle blade. This port will have very low or zero vacuum when the throttle blade is closed. When you open the throttle (give it gas), this port will have vacuum and pull the vacuum advance, advancing the timing. Also, if you have everything out of adjustment and the idle speed screw is holding the throttle blade TOO far open, you will have vacuum on that port. This causes incorrect idle speed, incorrect idle timing and dieseling.
Many people incorrectly connect the vacuum advance to a manifold vacuum port that has vacuum at all times except of course WOT. Some people think they have to have vacuum advance at idle, BUT they have made other changes to their advance curve to compensate.
When you set or check the timing, pull the hose from the vacuum advance canister and plug the hose. Leave the other end on the carb and plug the hose at the canister.
As Ken said, idle speed should be 600 not 750. You can idle it down around 500, but make sure the oil pressure doesn't drop off when that low.
Set the idle mixture screw to X turns out. Yes, I said X turns. X turns out is the point where the rpm stays the same when you turn it out, but the rpm's drop off like rock when you turn it in. This is called lean roll.
This isn't a fixed adjustment
Use a tach for the mixture adjustment. When the mixture screw increases the rpm, use the speed screw to slow it back down. Finetune the mixture screw again.
