Well, I'm a little cautious about giving advise on stuff that I haven't done personally, but I don't see any reason why it wouldn't work for a front fork provided you get the proper adapter for the caliper. Most times it won't work on the rear unless the frame has been designed for an 8" disc because the disc would hit the chain stay.
You didn't ask but, you haven't filed the lawyer lips off of your fork have you? If you get a big hand full of brake with an 8" front disc, the axle tries to rotate around the caliper and has been known to eject the front wheel.