Take it one step at a time. Try to eliminate the noise first with your new part by ''dry fitting'' the new part in and check for an improvement before a perminent soldering.
I changed out Lace Sensors in my Strat Plus for Samarium Cobalt Nickle pickups, along with a treble bleed capacitor........ I spent a great deal of time just thinking the process out........and before I soldered, I always dry fitted & checked it out by plugging in.....That meant taping wires down on pots and stuff before soldering.
Tape down a thick rag on you guitar body to avoid burning and splatters of molton solder.
Use a soldering iron no hotter than 40 -45 watts, and use ''heat sink'' clips ......dont know if you know this stuff or not....Just research web sites & get more/better adice from this forum before starting.
Please explain you problem some more....this ''all or nothing,''....could this problem be fixed by turning amp volume up more, and working your vol knob? And I dont understand why humbucker pick ups would make noise?.... Try plugging into a different amp to see if you get the noise.....? Thanks DAN
79' Epiphone Genesis Custom, 89' pre-reissue Les Paul Standard, 90'Strat Plus,
02' Tele (ash), 91' Martin HD-28, Epi A-12 acoustic, Fender Hot Rod Deville 2x12