I’d be interested to see the foam thickness Gary compared to your original.
The hump seat I have from Leightons is much thicker than my original seats.
Thicker than your seat was originally or thicker than you seat was beore 40 years of bums bounced on it.
Check the period road tests
A great number of them actually measured the thickness of the foam.
My original seal (apart from the cover being stained orange - hence why I didnt use it), had been off the road since the 70's so at best it had some ones backside flattening it for 10 years. I haven't removed it yet to see its compostion.
The original foams on my OIF (1 of which was like new) another came off a well used seat, but the thickness is still about the same. These also have what I can best describe as "pockets" in the foam, as opposed to the solid foam on all the new pattern seats.
Not relavent to this topic, but the one thing I can say about the original seats is the hump section and the slightly raised section for the pillion have all maintained their original shape (I have a bantam sport seat as well which is in great shape) The leightons seat.. Not so well, kinda looks like it melted.
I also found the leightons seat to be like perching ontop of the bike as opposed to feeling like your part of it, the BBB seat does feel more comfortable, in my opinon.