Burnt Clutches

My friend has a professionally built Powerglide, after only a few passes the high gear clutches burnt up. He took the trans back to the builder and had it repaired, the builder said he tested on his dyno after the repair and everything is good. He put it back in the car and after only a few chassis dyno pulls it smoked the clutch again, smoke poured out of the trans while revving it in neutral while setting the timing. This time he doesn't want to take the 2+ hour drive back to the builder and asked me to look at it. I have built a few glides that have worked well but I'm no pro.
So far we have done the following
-verified proper shifter alignment
-175-190psi at idle on the servo cover both in low and high
-175-190psi in high gear pressure port
-0psi in high port while in low
-sealing rings good
-stator support pinned
The motor probably makes close to 900hp and it had 8 clutches in the drum. Are 8 clutches adequate at that hp and psi?