I recommend somewhat longer focal length for 6X7. I personally use a 105 Apo Rodagon N, or even a 150 Apo N. An 80mm lens would be OK, but not ideal. Most El Nikkors are quite good, including the 80/5.6. The relatively inexpensive 75/4 is not, unless you use just the center of the optic for 35mm film. I do not know what you mean by "thick edges". If this refers to excess edge density creating pseudo-falloff, that's a development issue. Componon S is an older lens series of slightly lower contrast and a bit less less crispness than later lenses, but a distinct improvement over old non-S Componons. Some of these slightly older lenses are nice for color printing when you want to limit harshness.