For what focal lengths would I need the recessed lens board? From 180 and down?
I have the same camera and with 165mm SA and I shoot with regular lensboard. I think, you do not need recessed lensboard at all. You might need a wideangle (balloon) bellows for extreme shifts/tilts with lenses 210mm and shorter.
I use one down to 65mm for cool circular images. I gives me more movement and eases focusing. In the 180 range it is not needed unless you want more movement.
DIGITAL IS FOR THOSE AFRAID OF THE DARK.