Prabhupada installed them in any direction. I always have maintained that the rules of direction that describe it in Sat Kriya Sara dipika do not apply to the raga worship of Radha Krishna. However with Narayana ideally sadhaka should face east, thus the murti of Vishnu should face west. arcAyAM tv atha sammukhaH in Bhagavata 11:27:19, there is no instruction to use silpa-sastra or vaastu about Radha-Krishna, it is not under the rules of materialistic worship.