Factory tach not working with lq4

[Brettd85]

I’ve done some searching and read threads but there seems to be some inconsistent advice. My tach worked with hei ignition on my small block. This is a 71 c20 with factory tach. I installed a 6.0 lq4 and had the harness reworked by current performance. I connected the “tach” wire to the tach where the hei was hooked up. Not getting any reading. Some people say resistor, some people say I need a Dakota converter, others say program to 4 cylinder in hp tuners. Any advice is appreciated. Thanks!