Good to see somebody asking questions in this sub-forum again! When it comes to seats in Mustangs, we have done a few (and talk extensively about it
in this post).
Instead of regurgitating what I have written here and elsewhere about how bad the market is for side-mount seats, and why our seat bracket bases are better, I will talk about more of what the OP is asking about - tilt back seats.
We have been doing more and different seat mounting brackets for more styles of seats lately...
We have been selling and installing Cobra, Sparco, Recaro, Racetech and other brands of seats for ages, but Corbeau RRB (above - 2016 install at left, 2021 version above right) was always our go-to for reclining seats. These types of seats are more appropriate for a real street driven car, as a fixed back racing seat often makes the back seat inaccessible, are less comfortable on the roads, and fit fewer people. The styling can be polarizing but each model usually comes in 4-5 materials, options, colors, stitch patterns.
We just finished a new seat bracket design for this "bottom mount" reclining seat on my wife's C6, above. This is a Corbeau RRS seat, which is the same on the torso as the RRB, but is easier to get into (yet has less leg support as the RRB).
The C6 comes with absolute GARBAGE seats, which make the Mustangs seats look pretty good in comparison. On track it is like sitting on a park bench! We had to re-think our entire seat mounting bracket designs to work with the very different spacing of the bottom mount Corbeaus...
Above left is one of our many seat bracket bases for
side mounted fixed back seats. The width for the side brackets or sliders is VERY different than the
bottom mount sliders used on reclining seats like Corbeau. The sliders are also much more substantial on the Corbeaus, more like the OEM sliders - which are often part of the seat mounting structure.
Instead of re-designing our side mount style seat base brackets, we started over - and mimicked the OEM seat bracket/slider combos. We needed to add the tilt into the brackets, like the OEMs, so the seat sliders forward it also goes UP. On a side mount style seat we can just pick different holes in the side brackets to get the tilt right. Lots of other changes were needed, so it is a whole new seat bracket design.
Sadly we don't have an S197 or S550 seat bracket & slider for the tilt back seats, but we will take what we learned on this Corvette design and transfer that to these Mustang chassis soon (we have both models in the shop). Just something to think about for the future, if you are looking at a seat upgrade and don't want to jump right into fixed back racing seats...
Cheers!