Great. I'll bet they are plywood. The older manufacturers used plywood. MDF did not become available until the late 60s. Plywood is stiffer than MDF and will resonate at a higher frequency. It is also lighter and not as well damped. It is also way more expensive. Look at the back of the cabinet. If the rear panel is held on by screws it is for certain plywood. J Frum is correct in what he says from a modeling perspective but the equations assume an infinitely stiff structure in an anechoic chamber. They can not tell you what any given speaker is going to sound like in a real environment.
If I had those drivers I would build 10 cubic foot sealed enclosures 20" X 20" X 40". I would mount the driver in the 20" X 20" face and create a stand that held that face at ear level. I would cross them to subwoofers a 80-120 Hz and control the whole show with a digital preamp. Making it look good would be a challenge
In your case I would block the ports from the rear with plywood and cross to TWO 15" or FOUR 12" subwoofers using an active 2 way crossover. If you really wanted to get the absolute best out of the system and be able to tune it exactly to your taste get a digital preamp like the new DEQX Pre 4, Trinnov Amethyst or Anthem STR.
If you are asking why the strange shape (my enclosure), mounting a driver like that increases the stiffness of the baffle and places the mass of the enclosure in line with the driver minimizing the effect of Newtonian forces created by the driver. The small face minimizes enclosure effect which should improve the imaging.