salicaceae, how did you decide what to graft it on? It was my understanding they mostly graft Picea onto Picea, Acer onto Acer and all that.

They are both in the same family (Araucariaceae). But, being monotypic, Wollemia could only be put on a different genus for different roots. It is probably a bit closer phylogenetically to Agathis than Araucaria - but it depends on if you only look at DNA or also include morphology. It could be that the graft will not be compatible in the long-term, so it is an experiment. You are right about the norm of "Picea on Picea" etc. though.

I have some wollemi pines here doing well for me
must be the heat and humidity in SE USA that causes
root root.Im not sure that grafting on to Agathis
robusta will work in colder parts of the USA.

Very cool experiment ! ....sure beats doing it in Photoshop :O)