GSM is not a feel description
GSM describes mass per unit area. It helps compare fabric directions, but hand feel also depends on construction, yarn, finish and recovery. Give a target or range and state whether it is measured before or after the relevant finishing route.
Width and stretch need context
State usable finished width, not only machine diameter. For stretch, include direction, extension and recovery method where available. If those test details are not known, send a reference garment or fabric sample instead of inventing a number.