Poyudi Hytori
Honestly, Wearing both Integ and FF puts the drop rate for shadow orbs pretty damn close to 100%, if not at 100%. When at CL 11.4 and buffs R4ed
It's worth noting that CL doesn't affect Luck in any way, so apart from conning issues, your CL shouldn't really matter. Nonetheless, after the ~39 Luck you're describing (Fortune's Favor, Integrity, Divinity, Coyote Spirit, and Major Luck Boost) is applied, the base drop rate would need to be ~72% in order to reach unity. That seems to be a little higher than experience dictates, but since there's been no strong data recorded, the margin-of-error is potentially rather large.
If I had to, I'd guess the base drop rate is somewhere around 66%, making your drop rate with the above Luck sources upwards of 90% - close enough, at least, to feel like a guarantee... 3nodding