I have been in your shoes. Out here it seems that the only stuppliers that have any idea what soft firebrick is are pottey suppliers. I even contacted a "firebrick" manufacturer and when I asked for the "soft firebrick" he said "what is that" like I was screwing with him. Pottery suppliers, that is where it's at. The closest place I could find was in the SF BayArea almost 2 hours away. Luckily I have family that lives there that didnt mind trading an errand for knife
. They may even have refractory blanket and satanite when you are ready to do your forge! Good luck buddy. When you find the place that has it, you will be relieved.