Re: Custom 5 vs Gibson 57+?
Welcome aboard!
For a vintage tone, a '57 will be more accurate, but if you're playing classic rock and Chicago blues like I do, you might like a C5 best. If it's a little bright or scooped for you, put in an A8 magnet, which will make it a C8, a very popular PU here. Another great option for warmth is an unoriented A5 magnet in your C5, giving it more mids and less treble, and a lot of dynamics (overwound, but with more of a vintage feel).
We get our magnets from Addiction FX on eBay, big assortment and low prices. There's a video on Project Guitar.com that shows how to swap magents, which only takes a few minutes.