I'm a little confused. The racquet in my example has six holes in the throat, so why are you not clamping L1 and R1 at the head? Pulling tension on R3 would be triple-pulling since you didn't pull tension and clamp R1 at the head.I assume you mean this.
1) Clamp string L1 and R1 at the throatside.
2) String R2 and R3.
3) Pull tension on R3 at an adjusted 54 lbs.
4) Clamp R2 at the throat and release tension on R3
5) Readjust weight back to 50 lbs and pull tension on R3.
6) Repeat the same steps for L2 and L3, and continue stringing normally.
This is simpler and will certainly not make much difference:
You can also chose to pull all centre mains in the bridge at an average of 53 and because the difference will level out.
You can also level them “by hand” until the tones are about the same.