Likely the problem is, being it`s a Q-jet, the main wells are leaking down. This causes fuel to puddle in the intake after shut down, and the bowl has to refill hence why it takes longer to start. Quadrajets are notoriously famous for this, while it may not be the entire problem, being it`s as old as it is you can bet it`s playing a role. You can repeen the wells with a hammer and flat ended punch, then clean them real good and apply a epoxy to keep them from leaking any further. with the carb apart, place the main body over a bucket and fill the bowl with fuel and see where the drips are coming from, this will give you the clue where to peen them, after peening them and applying the epoxy, do the same thing to assure the leak is gone.