I have used both componon-s and el-nikkor, and both are excellent lenses. I would go for an 80mm. A 105mm lens is going to limit your maximum enlargment size, and if you are planning on using a receint model of enlarging lens the quality out to the edges will be fine. I currently use a Minolta 80mm 5.6 CE Rokker-X enlarging lens which is outstanding if you can find one.
If you really want a 105mm here is a nice one for you
http://cgi.ebay.com/ws/eBayISAPI.dll...category=30075