Haven't seen you post for a while Darrell ,always welcome your " 2 cents "
Remember Turbo Blue ? 20 years ago a station used to carry it in town...and 2 on the way to the track.
It will be happy days for him when he's down to reading plugs for heat range selection.Pretty sure somewhere
buried in the posts are factory recomendations for a base line.Colder plugs for towing.(racing) Don't know what year they stopped , but it was listed in the owners's manual. 64 I know for certain.