Grats, and you picked up duo-tanking on Hydra pretty quick, a lot better than some other people I've tanked that fight with :lol
You might be able to adjust gear a bit for a few points more of ss/det/crit by considering the EM primal accessories or Hero's but you're looking at probably single digit DPS differences if you're i90 because STR (assuming 100% acc) is the most important.
Allagan claws
Melee circlet
Allagan body / gloves / belt
Bananapants
Allagan boots
Allagan rings, maiming choker and ear, striking bracelets
I'm just missing the allagan body for this set which I built before EM primals were released but it's still a solid set. Will put me at perfect ACC and SS with a load of DET and some decent crit (considering uptime of IR and Bootshine's auto-crit, I prefer to go for DET more than crit but crit shouldn't be ignored). I eat HQ buttons for additional DET boost.
It's important to keep enough SS for around a 2.1 GCD for your rotations, so I need to test again but I think the allagan maiming bracelets would put my SS too low going from Melee Cyclas to allagan body (a loss of 24 SS, whenever I get the drop). If not, then all 4 allagan maiming are better (that's what I'm using right now, with banana body, since we only get tank and bard shit from turn 5).
This set gives you
STR 224
VIT 180
ACC 132 (IIRC 341 is the base ACC for a level 50 character so this puts you at a sweet spot)
Crit 168 (which sounds like a lot but this set isn't even going out of its way for crit; you get 73 just from allagan weapon and body alone)
SS 48
DET 74
Swapping allagan bracelets you get SS 32 and DET 85.
You could look for something else to swap on head piece to make up the ACC you'd need so that you could keep the allagan visor's DET, but your only other i90 ACC options for slots that don't already have DET on them are... Hero's bracelet (11ACC/11DET, so not enough on its own unless you ate ACC food). You could get EM ifrit bracelet for the ACC and lose the DET from allagan bracelet, netting you 4 DET from allagan visor at a loss of 10 crit. If you have excess ACC (like, with relic+1) the titan EM earrings are better than allagan but since we're talking BiS here then we're assuming you're building a set around allagan claws meaning you need more ACC from other slots.
Anyway, is it BiS? Maybe not. When you have the game's toughest content on farm does it really matter if it's a few DET shy of BiS? Nooooope.