IIRC my Dyna Coils leads were 7mm silicone leads with carbon core, lots on ebay in a choice of colours.
You will need the right crimp on connectors for the coil fittings if you make up your own leads, might work out easier to shorten a set at the plug cap end.
You have the option of going for copper core as well.
Updated
I bought my HT cable in the UK from the Green SparkPlug Co, they were 8mm not 7mm I checked my build log back in 2021.
You will find some in the US I would have thought.
https://www.gsparkplug.com/
