Disclaimer: I bear no responsibility for your safety or seat comfort in case you decide to use information in this post!
Some photos and more info for the tilt angle increase:
The 2 front bolts are M10 x 50mm ,
https://www.mackay.co.uk/m10-socket-cap-metric-head-allen-hex-screws-fasteners.html
you also need 4x M10 spring washers.
https://www.mackay.co.uk/washers-spring-stainless-steel-nutsboltsscrews-fasteners.html
Even though you replace only 2 front bolts, rear bolts also need spring washers for everything to sit securely and not come undone, as the angle has changed.
The actual supports are 12mm thick steel, 25mm wide and 12mm high, cut to 45mm length, with a 10mm thick solid neoprene rubber laid on top.
Steel goes at the bottom, rubber at the top to allow change in angle.
https://www.mackay.co.uk/flat-black-mild-steel-metals-warehouse.html
I got bolts, washers and steel from Mackay, though they are pricey for shipping. The nice thing about this shop is they cut your steel to order, so only drilling is required (pillar drill best for the steel and the neoprene).
But feel free to use other suppliers.
As I said earlier, I got short neoprene rubber strips from Ebay, search for solid neoprene rubber strip in about 25mm width and 10mm thickness. I would not go higher than 12mm with a neoprene rubber strip alone, you need steel underneath for support.
You can see front lugs in the photo, they still are in the floor for a few mm. There are also rear lugs I think, closer to rear bolts.
All in cost was about £15, plus drilling 4 holes (2 in steel and 2 in neoprene). Not much visible from top as there are plastic covers on rail ends, I had to put mobile phone right to the floor to make the photos.
HTH
Front supports:
Front bolts with spring washers:
Original rear bolts with added spring washers:
Disclaimer: I bear no responsibility for your safety or seat comfort in case you decide to use information in this post!