Be sure to inspect everything during the removal for any reasons to the failure. Recheck shift linkage in low and high , check the total amount of oil used on the fill as the trans was dry and converter was fresh whgen you installed it ,check dipstick calibration , converter to flexplate clearance when you undo it and push the converter back into the trans. Any of this information may help in the diagnosis of the failure, the rest is up to the trans builder.
Hutch