Our 43 would require a massive house cleaning to fit a 34. Most likely that's not going to happen. But, I'd be just fine with it. The reason we're a 43 team is that we were building upon Wake and Suh. IMHO, Wake could play SOLB if we had switched earlier, but at this point in his career, I don't see it happening. He's at the age where we're lucky to have him as a situational pass rusher. Suh, well he's a good fit for a 43, and honestly, he's our best defender by miles because of his consistency. Dominant, commands double teams, still disruptive, and shows up every game, and plays an insane number of snaps. I hate to say it, but Suh has earned his paycheck, despite our team's play.
Getting Ryan would be possible, but not likely. Wade Phillips was who I wanted, and that was indeed pulling a rabbit out of a hat for the Rams. But don't forget, they had some pretty good young defensive talent there too, so it's not like their cupboard was bear.
Ryan would no doubt produce a good defense, with more consistency and stout run defense than we've had in a while. For the past decade our defenses have been inconsistent. Sometimes great, sometimes good, sometimes not so good. Ryan would fix that and get consistently good defensive play. But, I don't think he'd sit quietly behind Gase, and without that, I doubt Gase would even interview him.