Well, without an existing one, at least your choice will be easier between a cover and a replacement. Without an existing pad, a cover won't work.
Your '77 may also have originally come with a colored pad, matched to the interior. Especially if it was a Ranger.
Only ones I've seen available so far were black. But many people use vinyl paint to restore the original factory look, and it seems to work well. So that's an option if black just won't cut it for you.
No pics, but I'm sure others will have some to post up. To my knowledge, your '77 won't be any different (other than color) to any other later year EB.
Here are images taken from our website of the early vs late pads so you can see the difference.
Early:
Late:
You can see how the early is basically straight across, while the late is stepped out to offer more padding for the passengers while retaining room for the driver controls.
Paul