My understanding of the work Ottussi did was to remove the leather from the cantlplate, reshape the cantleplate to narrow it and have it arched, and flatten the rear roll on the cantleplate.
When the leather was reattached the holes wouldn't line up so larger head rivets were required.
More on the technique: Brooks saddles - blocking and butchering!

Should be easy for RHM.
I did one in 2013 with hand made rivets.