As an update, I have just completed a tempo sink base and combined a 6" base in a single unit. Since it is a tempo, allowing me to move existing sink to its new location I made the face frame from material on hand (red oak). I built is exactly as I will a final piece, using FF biscuits for the face frame joints, and 20 biscuits to attach face from to carcass, as will as using them for the carcass joints. While I have not finished it, as yet, but plan to tomorrow after installing legs. I will take a couple of pics before and after and post them for some 'corective critisism'.
All in all, it was not a terrible task, in fact a bit easier than I had suspected (after changing the face frame dimensions, mid construction....
SteveA