440 flexplate/ torgue converter info

Looking for some info on flexplate vs torque converter combinations. Presently have a B&M 10237 flexplate married to a 3000 stall converter, 440 has cast crank ( rotating assembly has been balanced) as well as 727 has been rebuilt. Getting a vibration in reverse/ forward that follows rpm 1000- 3000. When I see the moon shaped piece out of the flexplate and no weights on converter can't help but think thats the issue?