Cool. What bike is it from? You will need a lot stiffer spring on it though. Then revalve the shock to match the spring.
I was able to use KYB SSS forks from the 2015 YZ450F on my MX without even changing the springs. I just shimmed the lower triple clamps. I used the YZ450F front wheel and brake.
Last winter I rode a CRF450 with a Pro Circuit motor and a suspension done by the Roczen's factory suspension tuner. It was valved for an A rider for the WORCS off-road series, so it was very plush, but the bottoming resistance seemed to be good enough for supercross. I didn't like the motor, my Alta's motor is light years better, but that suspension was out of this world. All the jumps appeared to be half the size with this suspension. I am sucker for a good suspension.