make the bolt length of the instrument to 95. this will result in 125mm length ((155+95)/2) = 125. I have no access to PDMS now but maybe others can verify.
thanks
since you're using old bolting method you will have to create another 600rtj flange with the same boltref as your instrument. Old bolting method is not capable of dynamic calculation which makes it a hassle to use for this kind of cases.
for PSV valves you will create MBOL containing 2 different BLTREF for inlet and outlet.
and for the flange that will connect to the inlet, in case the bolt thickness is greater than normal use the same solution as your 1st query.
