Here the 1905 LDS edition omitted the as from the LDS text. The 1911 LDS edition, set from the 1905 edition, maintained the shorter reading, but the 1920 LDS edition restored the as by reference to the earlier editions. The Book of Mormon text has only one instance of surely as without a preceding as, in 2 Nephi 24:24 (an Isaiah quote from the King James Bible): “surely as I have thought / so shall it come to pass”. The original Book of Mormon has two instances of “as surely as” (in Helaman 15:17 and here in 3 Nephi 5:24). And there are two more instances of “as surely as” in the current LDS text that derive from original “assuredly as” (see the discussion under Alma 37:45 and Moroni 7:26). In each case, the critical text will follow the earliest sources, thus “as surely as” here in 3 Nephi 5:24.
Summary: Maintain the expression “as surely as” in 3 Nephi 5:24, the reading of the earliest textual sources (𝓟 and the 1830 edition).