I'm attempting to add an original console tach and sender from a 64-66 Mopar to my 67 Dart GT's console. Since these were only used in V8s I was wondering if anyone had successfully installed one in a slant. A potential issue is my slant is running the GM based HEI setup. Here's a picture of the tach and sender hooked up and a reference source for RPMs from my timing light with the slant at idle. For what I'm trying to do the result seems close enough to proceed, but I figured someone in this august group may have been down this road before. The RPMs track pretty closely up to 1500 which is as far as I tested it. I adjusted the sender's potentiometer since it's a 6 cyl which moved the needle a little to the good. Also note the tick marks between 0 and 10 number 6 vs 9 after 10.

FWIW, I initially tested the tach with it on a table with the face looking up. The needle moved a little at zero with engine at idle and did move at higher RPMs, but not in sync with the timing light. Once I oriented as shown, it began to read more "normally". In this test the sender is getting tach signal from the HEI tach lead, 12v directly from the alternator, and both tach/sender grounded in the engine bay. The tach gets it's signal from the sender and is grounded separately. Once installed, the reading could get slightly more precise as the sender will be attached/grounded to the dash in addition to a separate ground wire and the tach itself grounded and attached to the metal console plate. Thanks in advance for any suggestions anyone cares to offer.