Century Spring product number C-333 is very similar in diameter (O.D. And wire) and just happens to be 9" long. You'd still have to cut the ends off, but there should be a tonne of these around.
https://www.amazon.ca/Century-Spring.../dp/B000BD6BUE
And I warned the woman I spoke to at Essentra Components to expect a surge of orders. FIRST can have that effect...
Jason