Have had the same problem + and idle adjustment problem as well. Took me a very long time to figure it all out. So you may be able to profit from my experience
This is what I did :
With a single plain she's going to need more initial than usual. It depends on the cam as well. You may need to go all the way up to locked advance. You will see idle stabilize and AFR's correct. Adjust it accordingly. Start with 18° and adjust mechanical advance to suit. Connect the vacuum advance to ported and have it add some 10-12°. You will find out you can turn the idle scews in a lot more this way. Get it approx good.
Pull the carb off, drain the fuel and clean it.
Reset the primaries and secondaries with proper transfer slot exposure.
Put carb back on, get it to idle right. If necessary turn out the curb idle screw but remember the amount of turns you turn it out so you can return it to it's Original position. Adjust the secondaries with the carb on the engine while running (you need a very short small screw driver for this - I modified one to do this). This may require some balancing : pulling open the secondaries some more until you have the primaries in the original position.
The thing is that I couldn't set secondaries on the bench, as there is some slack int the trottle opening mechanism on the secondaries (no spring etc.). So the vacuum of the engine pulls the plates agains the stop closing off the opening and reducing the amount of air the secondaries allow in. You will need that extra air from the secondaries big time.
If you do not have an AFR gauge. Use your nose. A bad idle mixture adjustment(afr ratio) will stink up your garage big time)
Then you experiment with the cam on the accel arm.
PS : I have a DP carb. May be a little different on a vac secondary. If you have to go to locked you might need a spacer as I've found my vacuum can hitting my fuel log line. Don't let it idle too low, use 900-950 as a guideline on a single plane.
I have also had some comments on speedtalk that the current fuel with alcohol in it, needs a different setting than what the old carbs were designed for...