This is why the 8.5 x 2.5 shock looks interesting.  It’s a very common size and broadens the options.  Even if it needs some minor finessing with offset bushings and/or some travel limit shims, based on the feedback it should be doable

That 200x57 may cause problems.

From pictures, there's around 63mm of "stroke" before the seatstays contact the seat tube. That's with a 210mm long shock. So when the shock is shorter than 210-63= 147mm, there's contact on the frame.

Your 200x57 shock, fully compressed, will be 200-57= 143mm, ths there's huge potential for a frame impact on chainstays arch.


The P8 with 57mm stroke should be around 136mm travel at the rear wheel.