I'm not sure if the arsenal photo is a very blurry one that can be found in wikipedia, but if it is, I doubt it shows any of the Whitworths. The guns in that arsenal photo seem to be some filipino made wooden guns, smaller and bit larger spanish bronze pieces and some mortars. Some really rare photos exist of the Whitworths in action at Mindanao against some moro cottas.
I know there is atleast one survivor (no carriage) in some spanish museum and I think I have somewhere a photo or two of it, but can't find those photos anywhere at the moment.