OK, I ran through some numbers ...
Typically a focal length equal to the diagonal of the film frame is provides a "normal" lens field of view.
Using the square root of the height squared plus width squared for a 6 x 7 frame comes out to about 9.3 cm = 93 mm for the frame diagonal dimension. The angle of view is about 53º.
Going into Pinhole Designer with a focal (pinhole to film distance) length of 93 mm, using 1.9, Rayleigh's constant, in the calculation, I get a pinhole diameter of 0.43 mm, which results in an effective aperture of f216.
If I use the constant of 1.6, which some folks use, I get a pinhole of 0.36 mm for f258.
For a bit wider angle by using a focal length of 60 mm -- approx 75º angle of view, I get a 0.35 mm pinhole diameter (f171) with the 1.9 constant. And 0.29 mm pinhole, f207, with the 1.6 constant.
Even wider, using 50 mm focal length -- approx 85º angle, I see 0.315 mm pinhole diameter (f159) with the 1.9 constant, and a 0.265 mm pinhole (f189) using a 1.6 constant.
In all, I used the PD default of 0.00055 mm for the light wavelength (green == mid-spectrum). Note that anything using numbers between those pairs of results will work, and indeed numbers some distance outside will also work to some extent. It's not a real tightly defined situation.