Trichocereus pallarensis is our scion today https://www.ebay.com/itm/Trichocereus-variegated-crested-collection-T-scopulicola-x-T-terscheckii-and/273205917805?hash=item3f9c57786d:g:rZQAAOSwZvFa9K9Y (https://www.ebay.com/itm/Trichocereus-variegated-crested-collection-T-scopulicola-x-T-terscheckii-and/273205917805?hash=item3f9c57786d:g:rZQAAOSwZvFa9K9Y)
Sorry, that was not the video.. here is the video https://www.youtube.com/watch?v=U2Q_HKxVQP4&feature=youtu.be (https://www.youtube.com/watch?v=U2Q_HKxVQP4&feature=youtu.be)
I'm also looking for this information as well.
My two cents... get a few pieces of Pereskiopsis to begin growing and a few to practice grafting with while you wait on your few pieces to multiply.