Which one of Bob Foster's opponents would you favour to beat Oleksandyr Gvozdyk?

I agree with Man-Machine.

Gvozdyk's a fine, textbook boxer-puncher, but there were tons of well-schooled guys like that with good movement and jab/punch-variety around in the '60s-'70s 175 scene (even during the transitional lull). He'd fit in fine with them, but is notably less proven against a variety of solid opponents than most. His skillset wouldn't stand out in that era, but nor would it be lacking compared to some of the relevant fighters like Quarry, Finnegan, Fourie. It's size and ranginess that I see as his main obvious advantage over quite a lot (though he wasn't a particularly "tall" fighting boxer overall, but still)....skills-wise they'd be close fights that you could find various advantages/weakpoints going both ways.

btw I think Fourie's an underestimated fighter, just one that is often fighting an obvious size and strength disadvantage for his style at 175. For a small (ex-middle) light-heavy that was weighing in at 168 for a lot of fights, and with no power (and bad hands), his ability to elude and frustrate Foster and fence with the bull Galindez was very impressive, with Victor needing late rallies to secure the wins, certainly more so than Gvozdyk's ragged after the early rounds effort against Beterbiev (who funnily enough reminds me a lot of Nazarov, seeing that thread about Orzubek pop up) and particularly as Fourie stayed at mid-range a lot of the time. Very relaxed, calm fighter with classy skills, particularly the jab; not a runner or a safety-first spoiler. one of those easily forgotten contenders that could well be a really tough head to head at 160/168 for somebigger names.