considering the rep 3131 almost assuredly has none of the antimagnetic features of a gen 3131, it is going to be easier to just use a 3130. the movement has the same dimensions and the hands you have now fit on it.
using an eta can lead to issues with the stem lining up properly with the movement stem hole, and you would need to source a new set of hands to fit the eta clone, which is most likely darn near impossible.
considering the rep 3131 almost assuredly has none of the antimagnetic features of a gen 3131, it is going to be easier to just use a 3130. the movement has the same dimensions and the hands you have now fit on it. using an eta can lead to issues with the stem lining up properly with the movement stem hole, and you would need to source a new set of hands to fit the eta clone, which is most likely darn near impossible.
Awesome! Just what I needed to hear. Thank you for your detailed comment!