Yes, I considered that too but didn't want to emend too much; I'm glad to have my suspicions confirmed by Ashok. For completeness, then, let me add that while यावच्चन्द्रः प्रभाकरः is certainly possible both metrically and with regard to meaning, यावच्चन्द्रप्रभाकरौ strikes me as a very plausible alternative.

Martin Gansten

Ashok Aklujkar wrote:
Two highly probable emendations for the defective verse have already been suggested. Suggesting a third one, दिवो for दिव्यो, I would like to translate the verse as follows: “As long as Indra is the lord of heaven, as long as the Moon casts light (and) as long as the story of Rāma exists in the world, may you remain in existence (or stay in power)!  यावदिन्द्रो दिवो देवो यावच्चन्द्र: प्रभाकर: । यावद्रामकथा लोके भूयात् तावत् स्थितिस्तव ।।