Ah! So an actual production ram board with a clock port does exist for the A600. Cool. Shame I only have the A601.

Looking at the Amiga Hardware site the A602 is shown as being a third party card made by 3State, and not Commodore as it might suggest by the A602 name that follows the official Commodore A601 expansion. However the picture of the A602 on that site doesn't show a clockport either. Hmm...