340 intake leak

There is no downside to running a PCV. NOT running a PCV has a couple of downsides.
Besides the above reasons for running one; Most carbs are calibrated to run one. The PCV is a calibrated,below-the-throttle-air-leak, and allows for proper synchronization of the transfer port timing. If you dont run one, you will likely have to increase the curb idle opening and very likely lose that sync. and run into tuning issues.
At high rpm theres a good chance the PCV will actually revert to near closed operation. Then the crankcase pressure has to find another way out. The factory solves this problem buy running a connector pipe between the valve cover breather and the air filter housing.
I have seen 2cfm going out the breather on a PCV equipped engine in good condition and not working very hard.Thats 2 cubic feet per minute.I have seen 4cfm when it was Wot. If it cant get out through a breather it will get out another way, usually messy.
If it needs 2 breathers the motor is either worn out, internally damaged,or working very hard indeed.