1st position blues : blues scale is +7 +8′ -9 +9′ +9 +10″ +10
top octave straight harp is fun if you can blow bend or want to practice it:
blues scale is +7 +8′ -9 +9′ +9 +10″ +10.
middle octave is overblow heavy for blues and bottom octave needs a 1 hole overblow for the minor third.
source: https://www.reddit.com/r/harmonica/comments/9xc2ao/1st_position_blues/