I am right there with you.
Due to the winters here in WI, I chose to go vertical. From my research, it will heat more quickly and being fire brick will have more stable temps in the cold.
My WFO is incredible at holding heat from even a small fire. I plan on using the same insulating concrete behind the split fire brick liner.
I plan to make a domed stainless steel inner liner for the ceiling with the top flue extending down into the cooking chamber (dimension not figured yet) to maintain heat and smoke.
I will be updating my build thread very soon as the rain and chit weather seems to finally be behind us now...
Not sure if this helps but some ideas from my research.
42" WFO,In Progress
-Brick vert smoker, Tuscan wood grill, 22" Weber, ECB-sent to the curb! Superfast PINK Thermapen
Offically a ZERO
"When it comes right down to it, you just want to be surrounded by good people and good food."