it's possible to do this but not in a way that doesn't involve some model work, sadly! simply removing the redirections won't work and replacing it with the standard iris material also won't work - his eyes are uv mapped to the two separate eye textures and cleared of their vertex color, meaning they won't be mapped right nor will they "dye" with the eye color.

the first way to do this that i can think of is lifting the eyes from the original head models & transferring them to the modified head models + reverting the eye material back to it's default, so the texture isn't doubled anymore and the eyes are properly mapped. you'll also probably have to do some material re-addition within the mod so that everything is pointing the right way... i'm not sure how familiar you are with those processes and i don't have the energy to explain in-depth rn, i'm sorry ;__; but hopefully at least that gives you a pointer to the idea of what you would have to do

the original actual 2.0 ver was supposed to include two versions of the mod - one with and without the custom eyes for this exact reason (which is why the one out rn is just named 1.5, it's sort of a 'lite' edition), but trying to get those both out really kicked my ass (hence the 2 years LMFAO) i may do the split a little later on when i'm not so focused on work. sorry if this isn't much help u_u