The way to have the most blank caseback that will fit a modern speedy to my knowledge is to polish off the hippocampus and the speedmaster engraving off a premoon caseback. Of course if you're going to do this PLEASE do it on a service part. (I'm sure your wallet will agree)
Otherwise it would be hard to polish off the engraving in the center in the modern models, unless you're OK with just only able to work around the sides.
Click to expand...