tachometer conversion on 72 Vette

[L88 crazy]

How do I convert from my tach drive tachometer to an HEI without a tach drive? I think sometime on the late 70s Corvettes had an HEI with an electric tach.

 

[Jack]

Use OE electronic tach from 75 thru 77 vette only. 78 & up don't fit. 74 & back are mechanical.
JACK:gap