I had a spec stage 3 in my 5.0 making over 500 rwtq on nitrous and it held it all day long. Hell with the break in period. I waited about 20 miles and did some donuts, thats how you break in new parts.
My good friend had the stage 3 + in his turbo'd cobra and it made 890 rwtq and he never had a problem with the clutch.
That sucks Spec messed up your order, but man we're all human and i'm sure you never fucked up anything ever. I'm sure you had plenty of time today.