341 hemi in 1970 dart

Yeah.......later they nitrided some of them that went in Chryslers if memory serves me. By the late 50's the writing was on the wall from a passenger car and production stand point.
Guys had journals hard chromed ( Chrom-a-shaft was one outfit that would do this )
The bad rap with nitriding has always been un-equal depth of treatment....it is essentially a case hardening and the number they shot for was .010 thickness...and often got .005 on one side and .015 on the other.
It still strengthened the parts , but until more advances in heat treat technology came along , it was as much a crap shoot as an improvement.