I have three overmelds in my crafter gear but I used decreasing materia tiers, typically V, IV and II. This helps keep the number of attempts required at manageable levels since each overmeld has an around 15% chance to succeed. While I can't quite macro-craft HQ Lv70 4-star from NQ materials, I can reliably HQ-craft manually (barring completely horrible RNG luck). My stats without any buffs are 1678 craftsmanship and 1628 control.