Funny string here, my tach guage went on my 72 coupe and while I was unscrewing the cable from the distributor my arm must have brushed across the oil pressure tube. I didn't notice until I started the car and saw oil literally spewing out of the engine, it was a gusher. If that tube broke while you were driving by the time you got pulled over the engine would be dry.

Great idea switching to the copper, I just re trimmed the end of the cable and re seated it but I still stare at the pressure guage all twitchy-like!