You may be able to fix this with a little machining and a thicker shim (if available). However the rest of the transmission should be made scrupulously clean because there maybe microscopic particles that passed through the filter and into the lockup converter and if you were to reuse it in the build you may be looking at a comeback. Also be sure to flush the trans cooler lines and the cooler itself.
I went through a similar problem when my wife owned a Phord Expedition. The first time it failed I pulled the trans pan and found enough aluminum chunks there to make a small block piston. The lockup converter was at fault. I went through 3 transmissions in that POS at $3K a time and the last time they replaced the radiator because the trans cooler was plugged up with debris. The truck is still in the family though now it is not my problem and it has been consigned to death at the hands of my sons employees.