And IIRC, Pat did that with just one C41 film, not several. Also, today's C41 films are very very different in composition including emulsion types and etc.
Yes, I talked to Pat about this and many other projects. At that time, he had a working color paper developer using CD4 and I told him what my dye stability tests looked like. He backed off.
Point is, unless you do a lot more tests than usual for APUGgers, then you run the risk of error. In that formula, maybe Portra 160 might work but Portra 400 would fail, or vice versa. IDK. Maybe neither would work. And Ektar would be a pain with its thin structure and 2 emulsion types.
Oh well, have fun.