If you're trying to chase Picayune, if I'm reading the notes on TobaccoReviews correctly, it's not an all-burley blend, but one that has flue-cured golden virginia, Samsun Turkish, perique, and dark fired burley. Five Bros ain't gonna do it on its own (and not even as an ingredient, except perhaps in trying to approach the purported strength of Picayune - but the flavor is wrong, not being dark-fired).
The reported lineup of leaves in Picayune puts me more in mind of C&D's Billy Budd Blonde (burley, cigar leaf, perique, virginia; just missing the dark fired and the Samsun). C&D Oriental Silk (oriental, turkish, perique, virginia) is just missing the dark fired burley. Briarworks Country Lawyer (black cavendish, cigar leaf, kentucky, oriental, turkish, virginia) has the oriental (not sure if it's Samsun), but it's not available in bulk. None of these are shag cut, though, and some bring cigar leaf or Cavendish to the table, so they're not perfect replacements.
One thing you might consider is D&R's Ryback. A shag cut that is cheap as chips and fairly strong on its own, it's dark-fired Kentucky, burley, and virginia. It's only missing the perique and the Samsun, which you can get as a blenders (Sutliff offers Blended Turkish, which includes Samsun, Yendje, and Basma; perique is offered by both C&D and Sutliff). I love Ryback on its own and I use it as a base in several home blends. It's fantastic, and if you started there, you may be 66-75% of the way to your goal.
One note I found in a TR review: "As a substitute, I like C&D Exclusive with a dash of Izmir and a dash of Five Bros."
