Diaphragm clutches take a lot less pedal effort. Centerforce is an example of a performance clutch that is low pedal effort. To install in your HiPo you'll need a new 28 oz imbalance flywheel that's drilled to accept the diaphragm clutch used on the mid-'80's Mustang. Ram Clutches sell these flywheels. Hayes too. You can have your existing flywheel resurfaced and drilled to accept the diaphragm clutch assembly.
With a diaphragm clutch, you may have to change the spring under the dash that's connected to the cluch pedal. Your present spring may be too strong and can overcome the Centerforce's diaphragm spring (meaning the pedal will stay on the floor after you disengage).
A weaker spring can be installed (some people take the existing spring off and don't replace it. I recommend you find a spring with about 30-50% of the existing spring force - not critical, just a lot less than the current one).
It is also possible you'll have to space the fork forward fractionally (1/8" or so). This means taking the bell housing off, removing the fork pivot rivets, making a spacer to fit under it, and then re-riveting it or bolting it. Note: the fork should be parallel to the back of the bell housing when adjusted and should not be angled forward. It may be angled forward slightly without a spacer but should not be far off parallel. If it is off parallel when adjusted and does not seem to work smoothly, this is likely the problem.
The end result of a proper modification using Centerforce is a clutch that operates and feels like a late model Mustang, but has a lot better grip than your current HiPo.
Note: Centerforce is also sold by Ford Racing. It grips better at rpm than replacement diaphragm clutches due its unique counterweight design.