Read your posts on the engine....and the"Tufftrided" crankshaft.
The process is a salt bath....Relative low temperature process that surface hardens the bearing journals.
Back in the days we raced drag boats....we would grind cranks on a regular basis.....but then ship them to the heat treat shop and have the shaft re-treated (Niriding on the steel shafts)
Tufftriding is similar to Nitriding...in as much as the process hardens the surface.
This is not a coating, but rather just a treatment of the metal....
Even grinding and polishing on a low performance engine will be fine......The Tufftriding was a way to add a lot of time to the clock on these engines. It also acts as a stress relieving process to help prevent cracking
We ran many Big Block Chevy's in standard form without treating. (Forged steel cranks (Nitriding used on the steel shafts)
The Tufftriding was/is done on cast iron (Nodular iron) to add a bit of extra wear prevention......