Nice photo but....
Just because an aircraft can bolt a particular weapon under it's wings or in the bomb bay doesn't mean to say it can actually carry it in flight. Although the MR2 could carry harpoon, I understand that weapon clearances on MRA4 have concentrated on the ASW weapon.
Granted, given a large amount of cash you will be able to clear storm shadow, but you will need to jump through a lot of hoops first. These will include:
1. Aerodynamic modelling for carraige and separation.
2. Structural instrumentation to see how the weapon impacts the wing bending moments in flight throughout the flight envelope.
3. Actual separation trials with inert and live weapons.
However, there are a couple of minor hiccups to this option besides the actual expense of the computer modelling and flight trials:
1. PA1 was the only structurally instrumented MRA4 which is no longer flying. Alternatively, you can instrument a production aircraft.
2. Hanging weapons under the wings negatively impacts lateral stability of the aircraft. Historically even the MR1 had to undergo modifications from the Comet namely the fin fillet to improve the lateral stability due to the negative impact of the large bomb bay doors. Looking at MRA4 photos with all the extra fillets added to the tailplane there may not be enough of a postive margin to the lateral stability to be able to carry underwing stores without redesigning the tail assembly.
On the positive side, given enough cash anything is possible.
Frustrated....