I would have the dash out to do it properly. It's another job you just need to be methodical with. However the 3 screws right under the windscreen at the back are a pig to get out. I had to remove just 1 last night to do the loom and 30 minutes later I still didn't have it out fully. Though it was enough for the job I was doing.
You have the help of a very, very good tutorial in this:
https://www.zroadster.net/forum/viewtopic.php?t=38747
The leather repair itself I wouldn't touch with a barge pole if I wanted it done preoperly. As some of you know I restore leather seats, I've repaired large holes, I've repaired bolsters, re-coloured leather etc etc. But I honestly think you're on to a loser trying to repair shrunk leather. Just the same as trying to shrink saggy leather on seats.
I would be asking a specialist trimmer like Bespoke Leathering or even Royal Steering Wheels. The leather is surprisingly inexpensive. But the labour is not going to be. If a steering wheel is around £150 I would guess £300-£400 if you were re-doing the entire dash. Which you might want to do to keep matching grain leather.
However if you don't want to spend that sort of money then gluing it back with the right glue is a lot better than nothing. I use this to repair bolsters, it's easy to apply, is very strong and works with leather too.
https://www.ebay.co.uk/itm/Trim-Fix...eather-Adhesive-Glue-Spray-500ml/223160081810