I believe that number is way too low to have originally been issued with an 1898-marked stock - if it were around 100000, I'd say such would/could be OK.

Will wait to see the pictures before making any further comments. First question though, are you sure it is 1898? Depending on wood grain, depth of stamping, wear, local impact damage, etc, it is possible to read a 6 for an 8 and vice versa.