Miller,
Your drilling is not from Suhl, rather it was made in or around Zella-Mehlis. Suhl didn't start dating the proofs until 1923 and didn't show the ledger numbers like Z-M did. You are correct about the nominal caliber of the rifle, but it was also sometimes called 8x58 1/2 R S&S.
The 59 just means it will accept a 59mm long case, by actual measurement. A nominal caliber designation doesn't always match actual measurements. Your drilling's markings are correct.
Mike