The compositor for the 1841 British edition set the conjunctive as as has, giving the impossible reading “all such has should come unto them”. The compositor may have misread as as has because the preceding word, such, ended in an h. Orson Pratt, in his editing of the text for the subsequent 1849 LDS edition, missed this typo; and the compositor for the 1849 edition, closely following his copytext (a copy of the 1841 edition), perpetuated the impossible has. But in the next LDS edition (1852), the original as was restored to the LDS text.
Summary: Maintain the conjunctive as in 3 Nephi 7:25: “all such as should come unto them”.