Tom,

I've got some B/W lightjets that were from scanned 35mm Tmax 100 that look pretty darn good up to 16x20. I would imagine that a ULF neg would make a really really nice large print, but it may be overkill. The viewing distance for such huge prints is pretty far. I don't know if the average viewer (photographer or not) would be able to see the difference between a print that big that originated form a 8x10 or 12x20 negative to tell you the truth.

If I were starting out with this in mind, I would go 8x10, drum scan, then lightjet. And make sure that the 8x10 has the best optics I could afford.

Brian