Judging from the pictures, the root cause of the failure was the plastic spacer ring in the rear clutch; when this spacer failed it allowed the piston to travel too far and pop out of its bore. When the piston leaves the bore the rubber lip seals expand and prevent it from returning, then the fluid pressure blows the seals apart. The lack of apply pressure causes the clutch discs to burn up. The plastic spacer ring is not a good choice for performance units, it should be replaced with an earlier steel spacer.

It also appears that there is a mismatch of parts in the rear clutch, a late piston was used with an early Belleville sppring, this might have contributed to the failure since the early Belleville is not as robust as the later version, especially when subjected to raised line pressure.

The color of the front band and clutches is red and they appear to be quality parts.

The pic shows the difference in the Belleville springs, the late type is on the left: