Most large format photographers (me included) would recommend a normal lens as your first lens. For 4x5 that would include 135 up to 210mm. Most 135mm lenses do not have a very large image circle so I would skip these as a first lens (I do love the 135 focal length). The larger the image circle the more room you have for camera movements. The most common normal focal lengths left are 150, 180 and 210mm. Any of these will do fine. I would recommend the 210mm because it is arguably the most versitile, it works great for most portraits (for head and shoulder shots you will probably want something longer), and it is inexpensive.
I would buy a Fujinon, Nikkor, Rodenstock, Schneider or Caltar in a modern Copal shutter. There is nothing wrong with using old shutters but as a first lens I would want something newer and hopefully more reliable. Pick any of these lenses as there is very little difference in sharpness. I would let condition and price guide me. Most large format photographers including myself own lenses of various manufactures. That's part of the fun of large format so don't forget to buy your Petzval later!