That earlier description of 1950s Mercedes bore-honing stirred some memories, weren't the later alloy-blocked McLaren CanAm car engines done that way? The process was described to me by one of the mechanics as "swirly-honing", it certainly sounds pretty similar, and as Lee said, surely modern rings and pistons would solve the problem.
I agree that You can reengineer the engines to work without the special honing tool and said aus much above.
and yes, rings, pistons, oil would be what you would look at.
Something else has ocurred to me in the meantime.
These engines have desmodromic valve actuation.
Not a big deal nowadays as hundreds of thousands of Ducatis run this albeit a different version with rocker actuation.
Remember that Scarab tried to make this work at the time and failed spectacularly, their engines would not even start.
You have to run very close tolerances on valve clearances otherwise you lose compression
Again, You can get on top if this, Mercedes are still running their cars the knowledge is there, but this might be tough nut to crack. Especially if You have to reengineer this without support from Mercedes.
I seem to recall that the system was not exactly designed for ease of maintenance more for high reliability, i.e. no screw adjusters but exchange of shims or even worse followers.