I am running Wilwood Brakes as well, also with a 7" dual diaphragm booster.
I also have a vacuum problem, so I went with a Hella UP32 vacuum pump (it has a 1200 hour life expectancy)-it is a vane pump used on electric cars, and I also wired in a vacuum switch to regulate the pump-
Everything was new, and I was quite unimpressed at first-here is what I learned:
-first off, I had a hard time getting a firm pedal-using a power bleeder solved that, but it took awhile.
-secondly, I have a Wilwood adjustable proportioning valve-adjusting that really helped, but I still wasnt satisfied-
-it took about 2-300 miles of variable driving to bed in the pads (which seemed like forever), but now it stops really well-
Doing it again I think I would add a 8" booster, but, like you, I'm out of room-
Drive it-a lot, and cycle the brakes-