Thanks.2 things can be done Malcolm now that I know what you are looking for:
1) it is common to indicate R8 for the root at the octave up. Since there is no mention of that in the bassline, the A# would be musically connecting to the bottom root a half-step from below since the major seventh it is not a great interval in a bassline.
2) would be the MIDI notation like someone mentioned earlier. Having B1-F1-F#1 and then A#0-B1.
Hope this helps
GM