from their website:
"Note: The original spark plug wire manufacturer for GM never standardized their wire script (font type, size, spacing, and text). Example: As shown in the photo below, the script on a spark plug wire for an early-build 1969 Camaro (top wire) could look significantly different than a that of a late-build 1969 Camaro (bottom wire).
We manufacture all our spark plug wire sets from original blueprints (which did not include wire script information). All our wire script information was obtained from original samples - Yes, we did obtain original samples on all the spark plug wires we manufacture!"