I had a lot of trouble gathering the exact info that I needed when i was trying to complete this project on my 1991 Legacy wagon, about 10,000 miles ago.
I ended up gathering 4 junkyard struts off of a 1997 Legacy "Outback" wagon. I then ended up swapping the springs on the rear struts, leaving me with 91 legacy springs and tophats on the 2 rears.
I decided to go with 27 x 8.5 x 14 general grabber AT2 tires, which lowered my gas mileage from about 25 to 20 mpg. Tires are unbelievably grippy and drive great.
Other than removing some underguard thin plastic and metal around the front tires, all that was required was some seriously hard hammering on the frame area front and rear behind where the strut sits. ( I believe this was because of the larger diameter of the outback strut perches )
I have pictures of my car next to a stock legacy i just bought, both are the exact same color, just so people can see the difference. I am really happy with the difference in drivability so far.
http://s457.photobucket.com/albums/qq298/contactrburns/Lifted%2091%20Legacy/ < --- link for pictures of car, " i hope "