73 Cougar electrical problem

Hoping someone can help me out. Several years ago I had to replace the battery cables, and ended up using the wrong colors for positive and negative to get a sufficiently long negative cable. When I replaced the battery, I had my head squarely up my butt, and switched them. Needless to say the car won't start now. I have replaced the fusible link, tried testing the cables for conductivity and the like, but don't know how far to trace the damage. I need to be moving the car soon, and need to get it running. Any ideas are appreciated!