I used the structure manipulation scripts provided by AIRSS to generate the conventional cell associated with your primitive cell. I think AIRSS uses Spglib under the hood for this task, so you could probably use Spglib directly if you wanted.
Original cell
New cell
POSCAR file
POSCAR
1.0000000000000000
10.0886200000 0.0000000000 0.0000000000
0.0000000000 7.1337300000 0.0000000000
-2.5221540330 0.0000000000 10.0886187273
A B
16 48
Direct
0.0000000000 0.0000000000 0.0000000000
0.4375000000 0.5000000000 0.7500000000
0.0937500000 0.2500000000 0.8750000000
0.0312500000 0.2500000000 0.6250000000
0.6875000000 0.5000000000 0.7500000000
0.0937500000 0.7500000000 0.8750000000
0.0312500000 0.7500000000 0.6250000000
0.5625000000 0.5000000000 0.2500000000
0.5000000000 0.5000000000 0.0000000000
0.9375000000 0.0000000000 0.7500000000
0.5937500000 0.7500000000 0.8750000000
0.5312500000 0.7500000000 0.6250000000
0.1875000000 0.0000000000 0.7500000000
0.5937500000 0.2500000000 0.8750000000
0.5312500000 0.2500000000 0.6250000000
0.0625000000 0.0000000000 0.2500000000
0.3750000000 0.5000000000 0.5000000000
0.2187500000 0.2500000000 0.3750000000
0.3125000000 0.5000000000 0.2500000000
0.1562500000 0.2500000000 0.1250000000
0.2500000000 0.5000000000 0.0000000000
0.1875000000 0.5000000000 0.7500000000
0.1250000000 0.5000000000 0.5000000000
0.2187500000 0.7500000000 0.3750000000
0.9687500000 0.2500000000 0.3750000000
0.0625000000 0.5000000000 0.2500000000
0.1562500000 0.7500000000 0.1250000000
0.9062500000 0.2500000000 0.1250000000
0.8437500000 0.2500000000 0.8750000000
0.9375000000 0.5000000000 0.7500000000
0.7812500000 0.2500000000 0.6250000000
0.8750000000 0.5000000000 0.5000000000
0.9687500000 0.7500000000 0.3750000000
0.8125000000 0.5000000000 0.2500000000
0.9062500000 0.7500000000 0.1250000000
0.7500000000 0.5000000000 0.0000000000
0.8437500000 0.7500000000 0.8750000000
-0.0000000000 0.5000000000 0.0000000000
0.7812500000 0.7500000000 0.6250000000
0.6250000000 0.5000000000 0.5000000000
0.8750000000 0.0000000000 0.5000000000
0.7187500000 0.7500000000 0.3750000000
0.8125000000 0.0000000000 0.2500000000
0.6562500000 0.7500000000 0.1250000000
0.7500000000 0.0000000000 0.0000000000
0.6875000000 0.0000000000 0.7500000000
0.6250000000 0.0000000000 0.5000000000
0.7187500000 0.2500000000 0.3750000000
0.4687500000 0.7500000000 0.3750000000
0.5625000000 0.0000000000 0.2500000000
0.6562500000 0.2500000000 0.1250000000
0.4062500000 0.7500000000 0.1250000000
0.3437500000 0.7500000000 0.8750000000
0.4375000000 0.0000000000 0.7500000000
0.2812500000 0.7500000000 0.6250000000
0.3750000000 0.0000000000 0.5000000000
0.4687500000 0.2500000000 0.3750000000
0.3125000000 0.0000000000 0.2500000000
0.4062500000 0.2500000000 0.1250000000
0.2500000000 0.0000000000 0.0000000000
0.3437500000 0.2500000000 0.8750000000
0.5000000000 0.0000000000 0.0000000000
0.2812500000 0.2500000000 0.6250000000
0.1250000000 0.0000000000 0.5000000000
I realize this isn't exactly what you wanted (e.g., the new cell vectors aren't actually orthogonal), but I am leaving it here because of the comments requesting for me to undelete the answer.