ditto I rebuilt the 283 in my dad's 1966 el camino. It too had the press on damper. I drilled and tapped. I heard from my uncle ( used to stock car race in the 60's in Ca) that gm used to beat those on at the factory with a steel malet. He said that it was hard on the thrust bearings.
BTW- kudos to you for building a piece of real gm history. Any shmo can build a high torque/hp 383.