you can bend a slot port, it's not advised to bend an aero because when you bend, theoretically it may introduce more turbulence. Aeroports are supposed to be used to rid as much turbulence as possible so it'd be a waste of design to bend aeros...
You can bend slot as i said before, just measure down the center of the port when calculating port length.
Whatever the total length needs to be, subtract 0.75" of that length if using 0.75" MDF as the thickness of the wall counts as port length unless you are running the port wall straight out the box and making it flush with the outside wall...
Anyways, whatever the internal width is of your port, divide that number by 2 then subtract this number from required port length and that's the actual physical port length you need to make. remember, just measure down the center to get your length. Keep turning the port 90 degrees until you get the right length.
Remember - if you are trying to achieve a certain tuning-
Increasing port area will only increase port length requirement.
Decreasing port area decreases port length requirement but may cause port noise. Try to stay within 12-16sqin of port for every 1cuft NET of volume internal.
Increasing internal volume decreases port length requirement.
Keep this in mind when trying your best to determine how you want your port to be made.