Interesting car.
Other great sleeper cars were the mid 80's LTD's. No, not the full sized ones, but the mid sized cars. I think Ford called the mid sized cars LTD's, and the full sized cars were Crown Victoria's.
Some LTD's came with the optional 5.0L V8, and they had about the same overall platform as the Mustang. That means most aftermarket Mustang parts were a direct bolt in replacement: engines, transmissions, axles, suspension parts, etc.