If you have 90\10s or 3 ways on the front and single adj on the back, you can only afford to buy 2 shocks, which one do you replace
If your car doesn't have a wheelieing problem I would go with rears. If it's pulling the wheels a lot then I would want fronts. But I don't think with your gears you have a problem in the front.
Brett Miller W9 cnc'd heads STR Chassis fabraction