999 clutch pack in a 904' & opinions on fluid

2nd subject; fluid. Having a Chrysler Torqueflite, I would be inclined to use ATF+4 fluid. Somewhere I read that aftermarket frictions (Alto Red Eagle)are designed with Dexron in mind. I have a L\U Torque Converter made for a Chrysler. Will Dexron fluid cause converter shudder, and\or will ATF+4 cause clutch problems?
Modern friction materials can run in any fluid without issue. I would not poor ATF+4 into a 50+ year old transmission that has never been rebuilt.
The standard fluid we use is DexIII on a basic, mild street strip build.