I installed a pertronix ignition on my 71 442 to get rid of the points and still look stock. The tach reads fast,with 3:55 gears,26.5 inch tall tires and automatic transmission, over 4 grand at 70mph. Has anyone else had similar problems and what is the fix?

 

I ran the Pertronix unit in my ‘71 442, and the tach was indicating correctly, check your connections again.

 

I also run a Pertronix in my '70 and its pretty accurate...

 

See the following from Pertronix but located on The Parts Place site: Pertronix Tach Signal Fixes.pdf
No idea if it will fix your problem or not.