Since having a pump fail late one Christmas Eve I have always kept a spare. At present I have a Grundfos selectric 15-60 which is almost new. However, instead of 1.5" flanges which fit tightly against isolating valves, this pump has 1" male connections at either side. These need to be enlarged to enable the nuts on the isolating vales to screw on and form a seal. What part(s) do I need to connect please ?