Well, the Fairmile Ds were powered by four Packard engines derived from, ha ha, the Liberty 12; so there's precedent. There doesn't seem to be any problem of principle getting an aero engine into an MTB, or a tank for that matter- think of the g force they're expected to tolerate; mechanical strength is not the problem.
Specific availability of specific engines from specific factories may be an issue, though; does Rolls Royce at this point have the productive capacity to do absolutely everything? Delegating to Rover and British Ford suggests not- and the failure of the Vulture can be partly attributed to designers being at full stretch already.
Specific availability of specific engines from specific factories may be an issue, though; does Rolls Royce at this point have the productive capacity to do absolutely everything? Delegating to Rover and British Ford suggests not- and the failure of the Vulture can be partly attributed to designers being at full stretch already.