How cold hardy are these two species? Would they do well in USDA z6?

I have a couple potted seedlings of A. spectabilis and want to know if it is worth allocating space on my property for them.

If A. gamblei would do well for me, does anyone know where I could obtain seed/a seedling/a graft? Sadly, I cannot afford a collection trip to its native range! Clement - I saw from previous posts you have a coning specimen of A. gamblei. Would you be willing to share some seed or scions?

Thanks all for the input!