I very much doubt that fat side up/down matters in foil.
It sounds right. And I would pay attention, cause once it comes out of the stall at 300F, it will climb fast. I use a probe method, it can be right through the foil if you want. I would take it out myself. It will be done soon I 300F.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
"perhaps...but then again...maybe not..."