If you can find it Benny Leonard's How to box from the 1940's is an excellent source on the right hand placement, blocking, catching, and parrying. Nat Fleisher also had a book by this name through The Ring on the same subject if its available still. I would never recommend a novice trying to learn from Jack Johnson's skill set with the low left hand. It worked for an expert like Jack but shouldn't be taught as such to Golden Glovers.
You are so on the mark about Rossman at his best like the Galendez and third Mike Quarry bouts. Text book placement of his hands for catching and blocking. John Conteh also held his hands high and blocked and parried with high skill.
I recently watched a chris john fight where he was blocking hooks with a salute defence from either hand.block and parry is one of the fundamental thing you learn in a boxing gym but still effective.
Nice catch. Duran also keep his hands and great postion to clip someone but also block and roll. Pernell Whitaker also was extremely hard to nail with combination because his hands were all over the place parrying and blocking shots. He made it an art. Henry Armstrong also used his guard like a shield meanwhile stepping forward like a Roman Legion.