Jason, here is the response I got regarding the crank question:
Hardening is rarely done on cranks meant for the street. In the
case where the cranks are cast, they are made from a hardenable cast
type material and the metal is pretty much the same all the way
through. In forged cranks there were some that were hardened but these
were generally engines meant for abuse, such as trucks or hi-po. You
will see some diesel cranks hardened, as well as those destined for
nitrous or blowers - all for the same reason. In these engines the
cylinder pressures developed (big explosions) are high enough where
surface treatment is considered warranted.
It does not appear from the traces normally left behind that the
Stovebolt cranks were hardened.
My crank grinder does a LOT of these for everything from street uses
to racing and has never had a problem with a crank based on surface
hardness. He does check the Rockwell hardness on the stroked cranks to
make sure there are no soft anomalies that could create problems, though.
I'd suggest that if someone is not convinced by this that they get
the hardening done for peace of mind. It certainly can't hurt and I
know some grinders who regularly harden (nitride) cranks for this reason.
