What is it about the swede's tone you don't like? I think that would be a better starting point.
The cavity is big enough to squeeze a 9V in it, more so if you stacked the knobs. So you could do it without devaluing her. But it's your guitar, do whatever you want.
I have played some 70's/80's swede's and I want one bad bad bad. I thought the pickups were very close to a medium output PAF. I can't imagine that you couldn't get the tones you were looking for out of them with a high gain amp or pedal. Unless there is something wrong, or they ain't original.
If you think the active tone (or absence of tone) is what your looking for, you might want to consider a different ax, you can find active equipped shedders from the 80's for less than what you'd pay for a set of blackouts. I honestly couldn't suggest a better passive humbucker to try as I think the swede's pickups are damn close what some chowder heads are paying 3k a piece for. That is, if you don't have a pair of mutts or some other issue.
You might consider and active boost, EMG, SD, Bartollini, Crack potz and several other companies offer them. They replace the tone control and offer line boost without degrading the signal. They usually go about $50.
PS If you do decide to install active pickups, I will buy your pickups for whatever you pay for the retrofit.