In which purana is vamanas's boon that bali would be indra in next manvantara is mentioned? Savarni=White? I've realised that vamanas's boon has been turned true, describes America's (Bali's patala) rise from past 500 years as world ruler
We find in Bhagavata
eṣa me prāpitaḥ sthānaṁ duṣprāpam amarair api sāvarṇer antarasyāyaṁ bhavitendro mad-āśrayaḥ
SB 8.22.31: The Lord continued: Because of his great tolerance, I have given him a place not obtainable even by the demigods. He will become King of the heavenly planets during the period of the Manu known as Sāvarṇi.
Else where it is mentioned that Bali becomes Indra in the next manvantara.
SB 8.13.12 — In the period of the eighth Manu, among the demigods will be the Sutapās, the Virajas and the Amṛtaprabhas. The king of the demigods, Indra, will be Bali Mahārāja, the son of Virocana.
This chapter of Vishnu Purana also says:
In the period in which Sāvarṇi shall be the Manu, the classes of the gods will be Sutapas, Amitābhas, and Mukhyas; twenty-one of each. The seven Ṛṣis will be Dīptimat, Gālava, Rāma, Kripa, Drauṇi; my son Vyāsa will be the sixth, and the seventh will be Ṛṣyasriṅga. The Indra will be Bali, the sinless son of Virocana, who through the favour of Viṣṇu is actually sovereign of part of Pātāla.