[pvan]

I was told over 5000 Big poncho converts in 69.
Of that amount only a few hundred were black exterior ones and of those only about 200 were 428's. I don't know how many 428 HO's were made and its noteworthy that my car had hand written notes on the build sheet from the factory that noted a cam, long branch exhaust manifolds, and #16 heads were shipped in the trunk to the dealer. When I rebuilt mine a few years ago it has 4 bolt mains and caps, factory forged pistons and some different then stock looking rods that were factory installed.
On the Canadian versions the small block chevy big ponchos were not that rare, I don't know how many were converts, but the big poncho with big block 427's chevy engines are really really rare.