That's what I reckon too (he'd make it into the later rounds, though: given his strong chin). If Bonavena didn't go the brawling route and chose to keep away, I reckon he'd have a very good chance (he certainly had the tools, though perhaps not the application). Tua TKO11.
Bonavena would have fought Tua the way he did Frazier and Chuvalo, and gone into his highly awkward, but effective "boxer" mode, and taken Tua the limit, and quite possibly would have beaten him. Oscar, like Gene Fullmer, was not strictly a come-forward, slugger type of fighter like George Chuvalo, but had a "reverse gear' that he would use when fighting a straight-ahead type of fighter.
