Just to add a bit to that... Make sure you don't get confused between the GR1 and the GR1A. The GR1 was the iron hauling jet, the 1A is the recce jet. Both have the laser-range-finder fairing under the forward fuselage. Agree with all of the options outlined by plasticmad. You could also add Alarms missiles on 7, 8 and 11; or a TIALD on 5. GR1As often flew with 4 fuel tanks, 2 hindengurgers on the wings and two of the smaller tanks under the fuselage (presumably on 7 and 8?).
Paul