Don't know the specifics on the Spec clutch -- it wasn't the "go to" when I bought my clutch/flywheel.
That being said -- there are two stock designs for the clutch and flywheel, pre- and post-TSB.
To make a long story short(er), if you have the old (pre-TSB) clutch and flywheel, you'll be replacing both, as the design got revamped. If you've already got the post-TSB setup, then your options are a bit more open (you could, in theory, replace just the clutch, or just the flywheel with some other ones -- I believe). However, as mentioned above, if you are going deep enough to change the clutch, you may as well just do the flywheel at the same time.
FWIW, I've got the Clutchmasters stage 1 with the light flywheel, and love it. Just enough of an increase in pedal pressure, without it being obnoxious -- and the lighter flywheel helps out a *lot* with the hanging RPM's that the SVT is so famous for...