The SPP message is like this
F2 LSB MSB
1 LSB = 1 step, 1 MSB = 128 steps
I think the easiest is to make correspond a row to a note value, mapped to MSB, so each row has to be 128 steps. Even for short pattern, it is doable with arranger Repeat, Length, Loop.
Might not work for original pattern lengths.
In that case, to play a specific step I’d rather use arranger Offset rather than LSB.