305mm G Claron for B&W work. It has a massive image circle (covers 7x17" stopped down), and is also corrected for closer work. It is a flat field lens, so shouldn't have much (if any discernible) distortion in the small part of the IC you'll use on a 4x5.

I've also used my 240mm G Claron and 355mm G Claron for coloured work, and found it to be a fine performer.