Huge +1 on the Camden. Also as much as I agree the mic fitting is more of a valuable pursuit than the preamp side, I also agree that a good mid-high end pre (as opposed to converter pres) will make many mics (including some very cheap ones) sound much better.
But the u87 on your voice vs the sm57 will likely drastically improve and fit the rock sound (or really most sounds) you're going for in a studio environment even on a $200 interface pre.
That said, the thing some peeps get caught up in is the semi-myth that the more expensive the mic, the better the sound, more pro, quality etc. I recently read a great post on a GS thread that mentioned something like how like 75 percent of the time high end / vintage mics will sound great on many things... But for a good number of things, certain less expensive mics work even better. Couldn't agree more. Love my Tonelux JC37 on about 60 percent of the stuff I track on my vox 3 x more than my vintage 87 that costs twice the price. Love my sm57 or date I say $20 Behringer mic on several of the songs I've written where for some reason it just KILLS on it for the live / raw / simple feel ... That said, I don't think I would agree if I didn't have a treated vocal booth / nice converters / high end pre to track it with.
But then I pop on my 87 and it's like that tried and true studio sound, which for some songs works well
Others waaaay too punchy, mid forward and alive sounding. This is what I've been starting to love about audio the more I learn and experiment... It's half a science , half an art. A fun rabbit hole to fall down... Doing things the wrong way can be so much fun too. Like I just realized the other day my low end Nady CM100 measurement mic (can buy for $30 used) SLAYS on classical guitar when tracked into the Camden and no compressor on the right gain setting / mic placement. I used to think man I gotta save up for a high end SDC like classical engineers use to even go near recording my classical ... But that Nady omg. It's lacking some low end (where u87 sounds much fuller on) but for that certain type of nylon string sound, it's just the ticket fory ears.
Sorry for the rant... Anyway, I love my 87 and can't recommend it any higher... The cheap clones of it nowadays , Serrano etc. are amazing and such a minor difference, many are selling their vintage ones.

Cheers!