I've done this two or three times. And the easiest way is too just get a set of 68 doors and hinges and modify the post to bolt the hinges on. Its actually very simple when you get into it. The only difference is the 67's have a cast hinge instead of the 68's stamped steel. The bolt pattern is different. Another way is to tack them in place and play with the gaps until your happy, then just weld the hinges to the post.