What I ended up doing on my last engine (475" Hemi), I took that High Flow and had a friend weld extra lengths to the vanes, then blued, fit, grind, repeat, without a gasket till the vanes just touched, then assembled with I think a .015" gasket. And yes I pondered heat expansion.

Haven't gone back in to see how things are going. 4500 miles later and temp gauge says we're still good to go.

Thought about a puller to move the vanes the roughly .200" needed, but went this route kinda just to see if it could be done.

I had some more aggressive vane ideas but went with the simple first and see how well it works and lasts. An experiment I guess.