Hi,
I bought a barely use Blue Point (Snap-on) double flarer from Ebay several years ago. The Lisle looks similar. Mine works great with no slippage and makes excellent double flares. You can get a good one for $40 to $50 like this which is what I bought and it had all the pieces.
https://www.ebay.com/itm/BLUE-POINT-...sAAOSwqzhegU1m
Skip the tube straightener. Buy straight lengths and trim for a custom fit. The Green Book has the lengths per model. I bought my 1/4" brake lines from Napa and made sure they pulled straight and unbent ones from the hanging rack.
Glenn