Actually, when I poked around a little on Inline Tube's site, I saw that they offered custom reproductions. I'm surprised they didn't offer this after saying they didn't stock the line for the 3.8 or Buick 350. I'm honestly surprised how poor some company's sales reps/procedures are. I sent another inquiry on this.
https://www.inlinetube.com/pages/duplication
https://www.inlinetube.com/pages/duplication