There are 3 yards in the Pittsburgh area with Integra type parts available that actually will do what you want. Check with All Foreign and Hemminger (near Jennerstown w 800#). There is also a yard in Cheswick I have dealt with and they seem to find this sort of stuff too.
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As for doing this project-it may not be worth the time unless you are completely rebuilding the rear suspension. There is no real gain in handling or braking versus drum brakes and the setup weighs more. If you proceed-buy EVERYTHING that goes with it. The yards will know what you need.