Hkj
Have him take itachis eyes. It will be useful for him. Amaterasu and Tsukuyomi are quite powerful techniques, along with the totsuka blade and shield. Itachis susanoo has very powerful artifacts. Like with the byakugan and so on he collected in the past, so that he can gain his new eyes, you could again do something similar. Itachis eyes… Rip sasuke then for no ems, but hey, if hagoromo can make one of sasuke ems into a 6 tomoe rinnegan, then making a mangekyo into eternal mangekyo is easy