V Beam antenna question

I want to put up a 40M V Beam antenna to enhance communication in one
direction only. From the limited design information that I have found, I am
thinking of 3/4 wavelength on each side with a horizontal separation angle
of either 72 degrees or 120 degrees. I have seen both separation angles
listed as optimum for maximum gain. I was wondering if anyone knew for sure
which angle would produce the best result. Also, and actually most
important, I need to have some idea of what the feed point impedance might
be. I can feed it with ladder line or good coax and a balun but I am not
sure what balun to use or would it be better to use ladder line? I sure
would appreciate any guidance on this antenna project.

Bob
W5QCP