For portraits, you're usually in bellows factor territory, so don't forget about that when you calculate exposure and set the power on the lights.
Even with the Sinar DOF calculator (and don't forget to rack the knob back halfway after calculating the desired aperture or refocus on the desired focal point), the attractive DOF zone for portraits is usually on the thin side, say from the tip of the nose to the ears. You can get more with enough light, but it may or may not be the look you're after.
If you do go for a thinner DOF range, the trick I use for portraits with a view camera is to attach a string to the tripod with a knot at the end, measure from the camera to the tip of the nose, and while the subject or assistant is holding the string in place, focus on the near eye. Then when you're ready for the real shot, after setting the shooting aperture and shutter speed, cocking the shutter, inserting the filmholder and removing the darkslide, you can check the focus distance quickly before making the exposure. It can feel a little silly, but it's very reliable, even with 8x10" and larger and a fast portrait lens wide open at f:4.5 or so.
If you can't do this (say you're photographing a toddler who doesn't know to hold still), then you just use more light, stop down more and make more exposures to be sure you've got a good one. Even with the string trick, I usually make a minimum of four, but typically 6-12.