This is my set up, I get pretty good results from it on higher level synths.
Careful synth until rainbow orb > Byregot's Blessing + Perfection* > Culmination** > Continue Careful synth until you get to under 11 durability > Masters Meld > Careful synth 3-4 times*** > Greater Calling > Rapid synth.
Congratulations you now have maxed your quality gain on a high level synthesis.
*They stack and it doesn't eat up a turn on your Byregot's Blessing
**Use while Byregot's Blessing is still active but if the next orb is yellow or white after Perfection I wait until the 3rd final turn of Byregot's to use Culmination
***Stop when you drop under 11 durability unless you are willing to risk your synth. Max loss is 10, min loss is 7 for careful synthesis.
-Side notes: My reason for this is that the BB + Perfection and Culmination combo gives you quality gains equal to 4 Great Success actions from careful synthesis and you get to control when you use it so you can max out your quality gain by using it on rainbow orb which gives you max quality output which should be around 130-160 quality per great success on rainbow orb. This also lowers your chance slightly of having your synthesis go unstable since rainbow orb has the highest chance of synthesis action failure and instability. On a higher level synth, you can't do better to my knowledge/experience.
Also for stats I'd take your control to at least 150~160 (160 being optimal, 150 being lowest you can get away with) and I'd take both Crafts and Mag Crafts above 120 at the very least, you will more than likely have to use food to get to this mark, and I suggest you lean your gear towards Crafts so you can make up in Mag Crafts with food since it is several times cheaper (I used Mulled Tea, it's cheap and good). This is much harder to do without a HQ tool with even just a single meld, so I suggest looking into one. You can dip down on the control to about 140 if you are feeling like risking an unstable for more Crafts/Mag Crafts for a higher end % on HQ.
It's also important to look into materia and jewelry for DEX (but not giving up your GC ring for a DEX ring) the increase isn't too much, but every bit counts.
In my opinion, this is a great way to make money since the NQ ores are cheap and HQ rose gold is expensive. Even if you can only pull 10% you will end up gaining in profit by a fairly good amount or save yourself a lot of gil if you were not planning on selling it.
Please feel free to leave feedback on my thoughts/experience if anyone has any experiences of their own. I hope this helps!