I used 3/8” nicopp hard lines with -6an fittings for TR6060. I also connected both hardline ends with a short flex line for ease of serviceability down the road. I’m pretty sure you can’t use the same flex line for fuel and oil. I went with Mr. Gasket push on style flex line. Their fittings are very affordable, no tools needed to install and don’t leak. Here’s a link to Holleys site, you can pick from the drop down menu fluid type and assembly method. It’s very useful.
https://www.holley.com/products/plum...ings_and_hose/