Relatively simple perspective question

[Ken Smith]

I'm going to show my public school art education here, but...

If I wanted to draw a 4x4x4 cube in two-point perspective, how can I accurately make the sides of the box (B&C) the same length as the height of the box (A), except drawn in perspective?

I understand I can do it with Plan perspective (which I have the barest grasp of), or just eyeball it, but I'm wondering if there might be a simple, but accurate method that I'm not aware of. The drawing I'm doing is somewhat more complicated than a cube, but this is the gist of the problem.

Thanks in advance.

Ken