Bandpass Design 2 12s

[all4spl]

Ok so I am again no expert, however an old friend of mine Will Alfonso suggested a BP design and below is what I came up with.

Specs provided where 5.7cuft 1:1 50sqin of port area 8" long.

After the suggested BP design I "tried" to mock one up in sketch up. I prolly got this all wrong but here is a picture of it with some area's left out to view the measurements. I shortened the port based on 1 shared wall, the way I got the length of the port of 5.25" is that I calculated the box like a standard ported box with torres calc at 50sqin 8" long, got the resulted tuning, then changed it to 1 shared wall, accounting for the difference of 4.5Hz I then adjusted the port lower in length till the same (within .01) tuning was obtained. I hope that made sense. Anyway here is the diagram/photo any input would be helpful as this is my first attempt at doing a BP design and I just kinda winged it based on the data given to me of 1:1 with 50sqin of port area 8" long.

The box is 1:1 2.9cuft sealed, 2.9cuft ported 50sqin of port area shortened the port length as detailed above.

Input? No flames por favor.