A518 Flex Plate Help???

Ok, so I just swapped out a 727 Non-lockup trans in my 73 340 duster for a lockup 518 trans. I went to bolt the flex plate to the torque converter, and only 3 of the 4 bolts will line up. I tried the different position, and still it wont line up. I looks like one of the bolt holes on the flexplate is offset, and is causing the problem. So my question is, what do I do now. Am I going to need a different torque converter, or flexplate? Any help would be much appreciated, cause I just can't figure it out.