Most vendors that can order the wheel for you should be able to find out what the (rough) weight of the wheel is, provided the sizing you want. It might be easier to find the weight of a more common Gramlights wheel with the same technology (C - 1P) such at the 57Getter, 57C6, and 57Xtreme to get a (again, rough) idea of what the weight of the 57Valkyrie will be.
There are images online, you just need to take the time to search through a few Japanese wheel and, or care review websites - that's what I did for my 57FXX wheels. Here's a pic I found just googling '57Valkyrie 86' -
I think that they'd look great on an RS 1.0 - bronze looks surprisingly good with the yellow (IMO.)