You could try adding 1 more black shim to #3 and #4 and see if that changes the sound by delaying the injection point a few degrees.
I would not change the rotational position of your temps are pretty consistent. All that does is vary the amount of fuel delivered with each pulse.
A trick to help assess the situation, seeing as you have plenty of extra shims is to loosen the bolt and cut a slit in a shim so you can slide it in without removing the metering pump.
Tighten it down and retest. If it makes an improvement, then remove the metering pumps and replace the slit shim with a good one.