500's were/are some of the heaviest of the early B's. Pretty cars though.
By the way, keep in mind that the 64' B's are just a couple or so inches longer and a half or so inch wider than the 65's. That with a slew of bigger elaborate front bumpers make for some extra pounds.

The 62' are the smallest, but open for debate on their handsomeness or lack of it. I personally love them all.
63's are in between with the weight but start to look fantastic.

These days, someones gotta take what ever comes on the plate whether it's a hardtop or Post. They are becoming harder if not, impossible to find in great shape unless of course, if you go raid Mosher's stash out West. LOL.