Have you tried a chevy dealer... a wrecking yard... . auto parts stores... . your neighbors restored 65' Nova... ?
I looked in my junk drawer and couldn't find one!!! lotsa other stuff tho.
I don't know about northern MN, but way out west, there is lots of performance auto shops that carry parts for those, maybe you could call a chevy fanatic and ask where to get something like that... . sorry I can't be of more help!
Make sure you get the same # valve, there should be a # (stamped) on the float bowl, Not the cast in one.
Good luck