Not knowing specifically the combination of factors involved in your install, just generally speaking, the "Long" style will have the greatest effort in the pedal.
The clutch at the other end of the effort spectrum is going to be "diaphram" style like the Centerforce.
The Centerforce specific to the Pantera is going to be a 10.5" od disc. Most aftermarket clutches are going to recommend an 11" for the Cleveland.
I was initially concerned with the holding ability of the Centerforce as a result but am agreeable that it is acceptable with no issues.
I don't see how the disc diameter would result in lower pedal effort but in this case it may? That makes no sense scientifically but there seems to be something to that.
If you are running a "stroker" engine with more cubic inches then a 351 (5.7L), it probably would be wise to use the larger disc but frankly all Panteras seem to be applicable to some kind of a various "witches brews"?
If you choose to go with the Centerforce dual-friction, be aware that the thing is "spooky" first installed and takes a bit of driving before it stops sporadically slipping mostly from at rest.
Centerforce does warn about that but the amount of slippage and the length of the break in period does seems to vary from car to car.
Just my observations, "your mileage may vary". 
Oh...one thing to add that may be significant...in the Pantera the seating position can effect the effort needed to operate the clutch pedal because of the leverage change cause by the seating position. Just something to consider?
Some vehicles do better then others with clutch type changes. For instance in a vintage Mustang, changing from the original "Long" style to a "Diaphram" style effects the entire design of the mechanical parts to the clutch pedal. The Mustang doesn't like the change.
The pedal stays noticeably lower then originally and needs help returning to where you want it. In the Pantera, that doesn't seem to mater because of the hydraulic system?
Additionally, the use of the "Long" in the Pantera originally seems to be a compromise and makes mixing ANY changes into the rest of the components problematic. The Pantera actually likes the diaphram type better. One reason being that a diaphram doesn't need as much travel to release as a Long does. Therefore, it's a better match to the Pantera then the Long.
I don't think that the various phases of the Moon have anything to do with it though...just in case you were going to ask but there may be more data on that of which I am not aware? You never know?