A good question. Often the punishments may fit the crime in Dante's mind (and theology), but won't necessarily fit them in ours.

I'm fond of Canto 23 of the Inferno, with the hypocrites walked in lead cloaks that have been gilded and the punishment of the proud in Purgatorio, where they are weighted down with stones for their pride. These seem related. That starts in Canto 10.

If you need it to be before that, I'd have to group the punishments of Limbo (Canto 4 of Inferno) with those in the early stages of purgatory (Canto 7 and 8), but I'd prefer the earlier comparison.