Second generation Camaro questions

[Dave Rifkin]

I was watching "My Classic Car" today and saw the feature on a Motion collection. When they looked the '73 Phase 3 Camaro the owner remarked that the car had started out as a white Type LT Z28 and Joel had changed a number of things to create the car that was being highlighted. This leads me to my questions:

1) Did all 2nd generation Motion Camaros start out as Z28's?

2) If not, did Joel convert any of the 600 L78 Camaros into Phase 3 Camaros?

I would guess that the owner is a member of this board and I must say he has quite the collection (green with envy).
He seemed like a really nice guy too; mentioned he also had a Motion Maco Shark under restoration.