Haven't made spark plug wires just yet, but I've been considering ’UTC Ultra Wire’ for the job. I think the ‘Brassie’ gauge could work well, as it holds a coil very nicely. I’ve included an image of ‘Medium’ gauge for size comparison only.

Available sizes: Large (26 gauge) (0.0180")
Medium (28 gauge) (0.0126")
Brassie (32 gauge) (0.0080")
Small (34 gauge) (0.0063")
Extra-small (38 gauge) (0.0040")
Cheers!🍺
—mike