I recently fitted a big redd piston and seal kit to a local members car.
Was I impressed with the kit.........no I was not, and I suspect the seals will not last very well, and the piston appeared to be machined mild steel.
I recall rebuilding the front calipers on the wife's Freelander, with a similar kit.....18 months later I did the job again using genuine parts as the dust seals had disintegrated.
Those seals are still fitted
Brian