OK, then get some clean lengths of hose, 'cause your mouth is gonna be your vacuum pump!
First, attach a clean hose to the "BOWL" (or "CARB") port on the canister. Attempt to blow into the other end of that hose. You should be able to do so very freely. If not, there's an obstruction that needs to be cleared, and/or the charcoal granules have settled and need replacement.
Then, attach that hose to the large-diameter "PURGE" port on the canister. Attempt to suck air through the other end of the hose. You should not be able to. Start the engine and run it at a fast enough idle that the vacuum advance port on the carb is providing vacuum. Disconnect and verify vacuum at the purge control valve connection on the canister (the one that's teed into the vacuum advance line), then reconnect it. With the engine still running at the fast idle, again attempt to suck air through the hose you've attached to the large-diameter "PURGE" port on the canister. You should be able to.
Let the engine drop down to regular idle, verify no vacuum at the purge control valve, and repeat the suction test. You should not be able to suck air.
If you get wrong (other) results with any of these tests, you will probably need to put in a replacement canister and/or purge valve. Hard starting is a classic symptom of a dead canister/valve. New ones specifically for old Mopars are N/A, but they are all rather universal as long as the one you use has all the same connections as the one you're replacing. How 'bout a brand new Standard-Hygrade CP1010:
or CP1019:
These are both in stock at www.rockauto.com ...
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So now, after driving around town some and the freeway, it takes more than usual to start, particularly after setting for more than 5 minutes. (More than usual is longer than a tap on the key it usually takes to start.) When the motor does start, I have to moderately rev it a couple of times so it returns to normal idle. I remember this happing before I removed the canaster...disconnecting the line from the carburetor vent to the canaster corrected hard starting. So, any ideas on how to correct this situation? 
I should mention I did Dan's recommended fuel line over the valve cover conversion, which I did long before I remove the canaster.