I did some looking and did not find a part number for 1500 Valkyrie.
This is an increasingly common problem because the 1500 Valk has been out of production for so long.
It doesn't mean they aren't made for 1500 Valk anymore, only that both manufacturers and sellers are not including the Valk in their parts listings anymore.
I saw a listing on Amazon for Cobra Swept driver's boards that fit a whole list of Honda Cruisers, but not the Valk. They may or may not fit the 1500 Valk.
https://www.amazon.com/Cobra-Swept-Front-Floorboard-06-4118/dp/B0082XHGH2I suggest you call Cobra USA and get tech help and a correct part number for 1500 Valk. Never buy direct from Mfgers as they always charge MSRP, and all aftermarket sellers charge less. Get the part number from Cobra, then shop the part number around for best price.
https://cobrausa.com/contact_us/ Phone: (714) 692-8180
I personally like the looks of the
Classic Cobra boards for Valk, better than the
Swept.
There's pair of used Classic for 1500 Valk for sale on classified, but they look pretty rough (driver or passenger?). There may be others listed.
http://www.valkyrieforum.com/bbs/index.php/topic,119822.0.html