Help With Port

[All Night Long]

I have a quick question about the port in the new box I am doing. The opening of the port is 4.75" and it L's at the back of the box and is exactly 4.75" from the back of the box like it's supposed to be. My question is I am trying to put a piece of wood in the corner with a 45 degree angle to create a better airflow inside the box, but can I do that without doing a 45 on the L of the port? If so can the face of the 45 be further than 4.75" from the corner of the L in the port wall? Because I cut some pieces of wood and just held them in place and once they are in the corner the distance from the flat spot on the corner piece is exactly 5" from the corner of the port L, which would be .25" more than the opening of the port. Is this okay to do, or should I cut new corner pieces that make the distance 4.75"? Or should the distance from the flat part of the corner piece be more than the 5" that I have right now? Is it okay to do a 45 in the corner and leave the L of the port at an L? The reason I am asking is because I don't want to match the port wall with the angle of the corner because it will take up more room inside the box that I need. If anyone can please help me that would be awesome. Some other info about the box is 4cuft internal with 2 DC level 4 12's tuned to 40hz. I am waiting on the subs to get back from being reconed and would like to have the box done by the time they get here.