with that cam you need to accecpt it got low vacuum, yourtiming and carb set up are dependant on the presence of vacuum. You'd be better with a double pump jetted square but you can tune a VS. Bin the vac advance, plug the ports and bump the static timing up to compensate.
Run the motor up to temp, stick a dial back timing gun on it. Rev and hold the motor to 4000rom, point the gun on TDC and turn the dial until your TDC marks line up. Read the marks on the dial, this is your total timing, back the revs off to 1000rpm, do the same and take a reading. Total timing minus static timing is the range of centrifugal advance you have. The curve plotted on a graphs would be RPM across the bottom, degrees of timing on the left. the curve statrs at say 14 degrees static @ 1000rpm and rises to 36 at XXXXRPM (whatever the total amount of advance is set to peak at, ie "all in by XXXXRPM") Now you know what you have in your dizzy currently. Pull the cap off, and work the rotor arm manually to move the baseplate. This is the movement made when advancing, the rate and total amunt of movement is normally controlled by small springs retaining weights. As centrifual force builds with rpm, the weights centrifugal mass increases and theythrow out pulling agaisnt the spring, moving the baseplate and advancing the timing. Light spring give lot of timing early, heavier restrict timing advance until higher rpm. The full extent of their movement will be governed by a stop of some kind, bending or modifying this will allow more or less total timing. So.....set the intial to you're desired amount, 12-14 should be OK assuming the motor can crank it over. Take a reading for total timing, then modify the baseplate to get your desired total timing, assuming it needs it.
Mixture. Forget the idle screws for the time being, these are finite adjustment for when you're close. Back the fast idle off completly to close the blades, people use this to get to where they want but invariably end up with an idle too high. By opening this, you uncover the transition slot which flows far more fuel than the idle micture screws. What you need is to promote engine signal with the blades closed. Drill a 0.8mm hole in each primary blade in line with the idle feed down the bore. This will increase the signal strength in the area of the idle feed without having to crank open the blades and increasing rpm. Start small and increase the hole size until till the idle mixture screws become responsive, ie you notice an affect by adjusting them. Your idle RPM should be reach with a combination of this, and a slight opening of the fast idle screw, quarter turn or so. If you have an AFR meter or lambda, at idle you want it fairly lean, 13.5-1 stoich or 0.95 lambda orhigher will be fine. By now you should have good control over the idle.
The response you get when stomping on the peddle will be governed by the pump shot, power valve and toan extent thetvaccum diaphragm spring. Pump shot is simple, go big till it puffs black out the exhause, then go down a size. Check you have sufficient clearnaceon the arm / mechanism, can't recall what it should be off the top of my head but 35 thou rings a bell ?
Power valves flow in the absence of vacuum, you sound like you've taken the vacuum reading and referenced the chart already. The vac secondary is essentially held shut by vacuum, as this cams got balls, you're low on vacuum,meaning they could be open too early. Wire the mechaism shut with some MIG wire and and see if the throttle is more responsive. Youcan adjust the rate of opeing by buying a spring kit with colour coded different strength springs.
Last point, if it's VS carb, the secondary jetting /metering is controlled by a plate. If you still have it, replace it with the kit they sell which allows you to add a proper metering block with screw in jets. Keep jetting up until your MPH at WOT starts slowing down, then drop down a size.
The above method of tuning has gotme and a number of mates very close of tune, you can get there, just need to understand what to adjust in relation to the engine signal.
EDIT - on idle speed, don't have it too low, remember you need splash oiling up in the cam area 1100rpm should befine
EDIT 2 - contrary to what some have written, vacuum advance, doesn't retard it advances timing. Vac advance increases the timing in the presence of vacuum to fire the plug earlier on the ignition stroke, producing a more efficient burn, thus reducing the amount of unburnt fuel exiting the cylinder when RPMs are low. A longermore efficient burn also puts the heat energy into the piston crown , bores and oil, thus reducing cylinder head temps. Try it, retard a motor whislt running, headers will glow red and temp will shoot up. By removing the vac advance, you need to bump the initial timing to compensate.