Hey Duffy as you might remember I was looking to do the same with one of my P90 guitars. At the time I was looking at GFS mini humbuckers. GFS had some issues with my ordering from Canada to have the pickups sent to Maine so it didn't happen.
Now they have them in a P90 style. I think they would be pretty good. They would be easy to mount with the screws provided.
They come with long wood screws and a piece of foam that you can put behind the pickups. When I ordered I asked for an extra piece of foam in each one. It would be pretty hard to adjust the pickups with only one piece of foam. You might want to do the same. I think for 65 bucks you can't go wrong. The guitar would retain the "look" of the p90. I wish they had some sound clips. Some people don't like the tone of a mini humbucker, but if it reduces the hum it will be all good.
It might be a bit of a decision as to what set to get, or a combination of both. Being you might not get too many reviews on them.
The Blues is alright!
Guitars: 1968 Gibson SG, 2005 Gibson SG Standard, 2006 Gibson LP Classic Gold top, 2004 Epiphone Elitist LP Custom, 1996 Gibson Les Paul Standard. 2001 Epiphone Sheraton II, 2007 Epiphone G400.
Fender Strats: 1996 Fender 68 Reissue CIJ, 2008 Squier CV 50s, 2009 Squier CV 50s Tele Butterescotch Blonde
Amps: Blues Junior Special edition Jensen in Brown Tolex with Wheat front, 65 Deluxe Reverb reissue,1970 Sonax reverb by Traynor, Avatar Custom 2/12 Cabinet with Eminence Legend V1216 speakers,
2008 DSL100 Marshall Amp , Fender Super Champ XD,Fender Vibro Champ XD
Effects and Pedals: Fulltone Fulldrive II, Fulltone OCD, Fulltone Mini Deja Vibe, Fulltone Fat Boost, Dunlop Crybaby Wah, Boss DS1, Boss DD20 Giga Delay, Boss TU2 tuner, Boss BD2, Ibanez TS9 Tube screamer, Zoom 505. Radial tonebone hot british.