no not really , just figure out what the volume of bracing you use, im thinking for the size of your box it would be around .125-.250 cubic feet tops , so minus that from the vb , it will only change the port length 1/2"-1" or so and 1 htz should not be too big of a deal ...
and you bracing should be front to back, side to side , top to bottom , just make sure it does not flex, you can use 2x4's mdf strips , round rods , any thing to brace it