I believe their plan with the prototypes is to stick them in the new museum at the McLaren factory. However, the F1 GT prototype has apparently been offered for sale in the past.
As far as the locations - three LMs are in Brunei - two of those three were apparently painted black instead of orange. As mentioned, one is in Massachusetts and the other is in Japan and the prototype remains with McLaren Cars.
There's some conflicting info on the whereabouts of the one of the customer F1 GTs. The burgundy one is in Japan, while the black one may be in England (with a customer) or it may be in Brunei with the LMs.
>8^)
ER