Good match up. Conney was a decent enough boxer, was bigger and had faster hands. Bonevena was certainly much tougher and durable, and had decent skills with some power. Could Cooney keep his composure and rebound if Bonevena knocked him down, or changed momentum? That is the $64,000 question. I lean towards yes, because Lyle did it. I'll go with Conney on points.
Bonavena was too strong and awkward for Cooney, who lacked the fast, sharp type punches that enabled Jimmy Ellis to be so successful with Oscar. In a sloppy, brawling, wild type of affair Bonavena would win a decision with a few knockdowns along the way. Cooney's chin was never worth a damn, and dealing with O.B. wouldn't be near as easy as facing an old, vulnerable Norton or old relics like Lyle and Young. Oscar showed that he was a tough nut to crack in his bouts with Frazier and Ali, and I believe that he would be too strong for Gerry.
Bonavena wins either by UD over Cooney, or stops him late, which is very likely under the right circumstances.
Bonavena would come from behind on the cards and stop Cooney late in the fight. Cooney's punches would have hurt 'Ringo' that much. Oscar was too tough.
IMO Bonavena hits the deck a few times, but also puts Cooney on the deck a few times himself. And takes a hard fought unanimous decision.
He stopped faded versions of Norton, Young, and Lyle... but he did it in a brutal way (Norton and Lyle anyway). He gave Holmes a few fits before being stopped in the 13th round. I doubt Bonavena would have done as well had he switched places with Cooney.