Swaggasaur, I just realize you can't do 13 height port if your boxt is 13 high. 13" high box minus 1.5" (0.75 top baffle and 0.75 bottom), leave you with only 11.5 hight of port. With port being 11.5 high, max port width is 4". Min width is 3". With 11.5"x3"x 26" of port, will give you your desire tune. But box will be too small, 2.76 ft^3.
If that's all the space you're willing to sacrify, I would recommend doing tube. take less cube for tuning.