I have doubts about whether Vegeta SSJ3 (S17) would be stronger than Goku SSJ (S17), since Goku saw how Super # 17 left Vegeta SSJ2 very hurt after giving him 4 hits and even so, Goku SSJ believed that he could defeat Super # 17.
Even at the beginning of the fight, Super # 17 goes at full speed towards Goku SSJ and he dodges him, then he hits him and sends Super # 17 to fly. Later Super # 17 easily hits Goku SSJ, that only indicates that Super # 17 got into serious fighting only when he was outmatched by Goku SSJ (S17).
Nor do I think that the Final Flash that absorbed Vegeta, has strengthened him much, since Vegeta when he launched the attack, was transformed into SSJ, while Super # 17 (Initial) should be superior even to Vegeta SSJ3 (S17).