I recently recovered an old vinyl Brooks saddle (from a Raleigh Sport) with leather. I used 3M 77 and clamps to hold it around the edges. It turned out really well except for near an area where the original seat liner was torn and the plastic underbody had shattered. I had layered some strips of duct tape to reinforce it but there is a wrinkle where the tear/cracked vinyl is. But for a $9 scrap of leather it looks (and feels) so much better than the original malformed saddle. If I'd do it again, I'd find a better way to reinforce the plastic underbody, but nothing liked sticking to it.

Your saddle looks very nice. Great work!