Here's a link to the SM-1.
http://www.seymourduncan.com/products/e ... ntage_min/It IS a Firebird style pickup, except with the ugly embossed logo. I'm PRETTY sure the Gibson covers would fit, but would make the Gibsons unsellable & you could get more for them than the SDs would cost ou, especially if you are patient & get some used! Here's a link to the covers, they're only $30 & you could probably get them cheaper IF you can find a dealer, or maybe even used.
http://www.allparts.com/store/mini-humb ... roduct.aspThe SDs will fit the cavities with no mods.
As to cover removal, I simply heat the solder with a LOW wattage iron & remove the solder with wicking or a suction bulb. While the cover is warm, not hot grip it firmly & gently work it loose. Be patient & it should be fairly easy. Just work slow & keep the heat low. When putting new covers on, I simply put a bead of silicone on the magnet in the center of each coil, clamp the cover to the base plate, with something to protect the cover from scratches & put a bead of solder on each side where it was before. Just don't overheat the base plate when soldering.
It's really very simple...after all...I can do it! Just remember...work slow...heat low.
I hope I helped.
Tony