I have a post that measures 4 1/2 X 4 1/2 assuming is is a 5 X5 post. I need to sister from base to about 1' to 2' ft high because it's rotted at the bottom. I went to lows and they only sell a 4X4 or 6X6. Nobody sells a 5X5. Anyone have any suggestions? I'm assuming I can get a 6X6 and cut 1 1/2 '' off. How would I go about this. Table saw , hand circular saw etc.