The general rule that I was taught for traditional portraiture (above the belt with the head) would be the sum of the two film sides (9 inches for 4x5, so, slightly telephoto).[/QUOTE]
I had never heard that, what a great trick!
For big face LF portraits I find a critical feature in a camera is back focussing. Front focussing cameras change the repro ratio as the lens moves back and forth. In the worst case a front focussing camera will deliver various size blurry faces but never actually deliver focus at any point in the entire focussing travel.
Another vote for the studio stand as the support mechanism of choice. For the camera, any tailboard/rear-focusing camera would be good. I'd go for 8x10 if that's not a budgetary issue because there are a TON of portrait lenses out there made for 8x10. Bigger sizes are cool, but other than 11x14 you're talking annual special order for film, and significant increase in all other costs. Weight also becomes an issue. Going above 11x14 you're looking at getting one of the Foba or Linhof studio stands and spending a small fortune on getting it. I have an INKA studio stand which does more or less kinda sorta work with my 14x17, but it's not entirely happy with that camera. Some of that I think is limitations of the camera design - it's a Canham 14x17, which gets wiggly at portrait focusing range. A 14x17 head and shoulders portrait is in the 1:1 macro range, so you're talking about adding at least two stops of exposure compensation for the bellows extension.
Here's a close-up shot of it, and the following shot is a wide shot showing the camera on the stand in my old studio.
Bear in mind also that with an 11x14 or bigger, at portrait distances the camera will all but require two operators, as the bellows will be so long you can't operate the shutter controls from behind the camera. Because of those huge bellows extensions and the price of ultra-large format film, you may find you need those strobes you eschew after all - nothing says no repeat business like a second re-shoot because every shot was blurry from too long an exposure and/or insufficient depth-of-field. Minimum DoF for 14x17 to have an acceptably sharp portrait? minimum f32 (which means you need to hit f64 in terms of light level). No way you're hitting f64 worth of light with daylight faster than 1/15th or 1/8th of a second, even with HP5/Tri-X.