166K MP if you find some ( PN P4876878AB )... I got one 175K used coupe of times after a fresh Chrysler remanufacture ( still on its box ) in barelly $75, but I THINK for a 400 with HP camshaft 166K is way enough.

the hard part is get one at this moment since they are discontinued now.

With a Charger born in Chrysler assembly plant in Valencia, Venezuela