Yeah Killerbee stand very good chances. strong body and good swordstyle and perfect jinchuriki. can use chakra cloak, biju cloak and can turn into a biju
Naruto wasn't alone, had like five frogs at his disposal.
He prepared two sage clones and had information on Pain.
Would have died but Pain's goal was to capture him, not kill him.
Anyways, you just listed Bee's abilities. That doesn't mean anything.
six path of pain will beat him and absorb his chakra , the eight tails can't escape chikabi tensai it was only the raw power of naruto full nine tails to escape the jutsu.
Pain would win. Chibaku Tensei, 6 Paths, Chibi (or "Cerberus"), gravity manipulation, etc.
Plus Naruto wasn't alone as someone else said. Pain fought all of Konoha, he wasn't even going all out in the fight, and Naruto knew Pain's secret.