I am building a ported box for a 10 inch Solo-Baric L7 I have questions.

1.75 cu.ft. + port
2.75x11.25", port 17.75" long

1.75 cf, Fb=42Hz
.32 cf = Port Vol
Kicker specs.

Question 1
I need to modify the port. I am useing an old box that I built.
I am under the impression I have to keep the port the length it is, wich is 17.75.
The box I am useing is taller than the box Kicker offers.
Is it fine to change the width and hiegth from 2.75x11.25 to 2.5x12.5
Area for the 2.75x11.25 is 30.93 square inches.
Area for the 2.5x12.5 is 31.25 square inches.
Those numbers should be close enough.

Question 2
My other question is about the Fb.
If I am not mistaken the Fb is where the frequency starts to roll off rapidly.
With the specs above, the Fb is 42Hz what do I need to do to lower the Fb so its somewhere between 35 to 39 hertz?

I have a 3rd question if the port Volume is .32 cf can I manipulate the LxWxH of the port any way I want as long as my final port volume equals .32 cf?
Thanks for any help.