Hard to start, found problem. Now Why?

Years ago, engines did not have PCVs. Instead, they had road-draft tubes. An Engine would have a tube leading from the top of the engine down to about 6 inches from the road, and slash-cut, so that the air passing underneath the chassis, would draw out the blow-by as the car moved down the road. Idling at a stop,, they would sit there huffing the smoke into the air and stink up your clothes, and interior.
The point is, that the crankcases were still ventilated.
And the carbs were not calibrated for PCV.
So the conclusion is that your engine does not absolutely need a PCV; but it absolutely does need to be ventilated.

Now;
if you have a carb calibrated for a PCV, such as yours, and it has a starting problem that goes away when you plug the port, you only need to think about it to quickly conclude that your engine wants; a lil less air, or a lil more fuel, during cranking. When you plugged the port, you forced the engine to pull harder on the transfers, and on the idle-discharge ports. So it got the fuel it needed. There are better ways to meet the engines needs during cranking than plugging the PCV port.
The PCV is just a spring-loaded, variable-flow, device,with 4 modes of operation;
1) it has a fixed minimum flow, in response to a high vacuum
2) it has a fixed maximum flow in response to little to no vacuum
3) in between those two it has a variable flow, as calibrated by the spring fighting vacuum
4) it has anti-backfire protection to prevent the crankcase from exploding if there is a backfire in the intake with the throttles closed.

During cranking, there is no manifold vacuum, so the valve will be at maximum flow. No big deal for a carb that is calibrated for it, on a healthy unmodified engine, running the factory timing....... because the throttle will be in the right place for the atmosphere to push fuel out the float bowl, up the idle wells, over the top where it spills out the transfers; to be mixed with the air that is pushing past the throttles. Simultaneously, additional fuel will be discharged from the idle ports, and Air from the PCV system completes the picture.
This assumes three things;
1) the float bowl is connected to atmosphere via the bowl vent, and
2) there is fuel in the float bowl, at the correct level.
3) that the throttles are sufficiently open

That # 3 is the first thing that gets screwed up when somebody cranks up the timing. More timing increased the engines efficiency, so the idle-speed goes up. So in response, you back out the speed screw to slow the engine down. But now the fuel supply from the transfers is wrong, so in response, you open the mixture screws. Now it idles at a reasonable rpm.
But your engine doesn't idle all day, so when you put it into gear,this loads up the engine, so she slows down maybe a hundred rpm, maybe 150. and this slows the airflow past the nearly closed theottles, the fuel stops flowing, the mixture screws are maxed out... so she stalls.
So what do you do? Well heaven forbid you put the timing back; no, you increase the speed screw setting, which restores the fuel flow, but now the neutral idle is ~150 higher, so when you put it into gear; BANG, the U-joint take a hit. And air flow again slows down past the throttle blades, but at least id doesn't stall. But it sure pulls hard while waiting at a red-light.
So what do you do? Well heaven forbid you should retard the timing a few degrees; no, you go buy a hi-stall TC, cuz you're getting tired of the constant banging into gear, and the constant pull.

Now lets complicate that with a plugged PCV port shall we?
Now, Unless you have a big cam of say 230* @.050 or more, or for whatever reason your idle vacuum is so low as to put the PCV in or near WOT mode, your engine wants that missing PCV air. You can tune the idle to run without it. But as soon as you tip in the throttles, the engine will go rich. Once on the mains, she may not noticr the missing air, cuz you can downjet in compensation. But at Part Throttle, while on the transfers, the engine will be rich all the time, and you may wonder why your little engine gets such lousy fuel mileage, in spite of the crazy timing you keep throwing at it. Heaven forbid you should put the timing back to stock.
The timing your distributor controls is your power-timing. It is only correct at WOT; And only if you have made it so.
All iron-headed gas engines will want about the same ignition timing after ~3500 rpm. I mean give or take a couple of degrees. But the problem is below that. Every combo is different. But the one thing that is constant is that no matter what timing curve you work out below 3500rpm, it will only be right at WOT, and only if you make it so.
The rest of the time, your V-can is in charge.
Except at idle, because the spark-port is dead.
At idle, the transfer exposure under the throttle blade is in charge. Set that right, and use the timing to set the idle speed, and twiddle the mixture screws for best idle and freedom of tip-in hesitation.
If your mixture screws end up to far open, then increase the transfer fuel, and back up the mixtures. If the idle-speed rises too far, retard the timing.
If your mixture screws end up too far closed, reduce the transfer fuel, and open the mixture screws. If the idlespeed is too slow, increase the timing.
Of course this assumes the PCV is working, and in the low-flow mode. and that the doggone bowl-vent is open. and the doggone fuel level is correct.
Ok bed-time now,lol.