rears will bolt in, may need to tyrim the parcel shelf supports a bit and iirc you need to change the upper retaining pins for longer ones?
fronts you have 2 options, chop one of the legs off and reweld it further in, or swap all the backrest, base foam and fabric on a 90spec mk2 seat base frame. only issue with doing that is the plastic tray round the bottom of the seat wont fit back on and the height adjust handle is in a different place. just means there will be some holes in the fabric is all