I would rate him probably around the #8-12 range of the all-time LHWs & in the all-time top 40 (perhaps even top 30?) P4P. He beat an already-established Great in Burley in his very 1st year as a pro & had an ATG unbeaten streak from '42 into '46 in which he decisively beat 2 of the best ever in Charles & Moore. @ one point, he was simultaneously #1 ranked @ both LHW & HW & he would've been a shoe-in to win the LHW title if it hadn't been frozen by the war. Once Louis entered the military, Bivins was arguably the 3rd best P4P fighter in the world behind only SRR & Pep. Shame that his career declined just as the champions were returning from the war.
His June 1942 to Feb 46 run is only rivalled by Tommy Gibbons 1911 (I.e. his debut) to 1920 run, as the most underrated and/or undercelebrated run in all of boxing history, imo.