use the shock as-is, and add rear sag to compensate for the 10mm extra length.
there will be an advantage to having extra drop in back...improved ground contact, and a bit more cush when landing.

and the front angle change won't be enough t worry about anyway,,, you won't notice it at all, if it does change a half degree.

https://mtbdatabase.com/bikes/2014/g...trance-27-5-1/