Does anyone know where I can find standards on pruning weeping ornamentals?

You do not need any standards other than the normal crown cleaning guidelines, other than your personal preferences, as it is your tree/\.

It isn't clear to me what your intended application of "standards" would be (e.g. commercial landscape pruning, or private use).

It occurs to me that, other than the pruning standards applied to other trees (target pruning, dose, thinning cuts, etc.), weeping trees might have a couple of other considerations:
1) If they are flowering trees, then you need to consider the effect on flower production and display.
2) Sometimes weeping trees are subject to sunburning on the tops of branches, where they present an unshaded face to the sun. Scalding can lead to necrosis and decay. In that case you may want to consider leaving as much shading material as possible, or even paint the branch tops with white interior latex to reflect heat. This is sometimes done on peach and nectarine trees, which are "topped" at harvesting height and where weeping branches bear much of the fruit.