it would take two vulcan's rings and I can't remember ever seeing one
That is because (correct me if i'm wrong here) Vulcan Rings are in the data files but do not actually exist, i have talked with many of the level 100 goldsmithing crafters and actually one of my flame rings was HQ'd however the HQ is the same as the NQ, Vulcan Rings are not implemented in the game. As far as max str, count it up:
Shinsoku: +5
Arco de Velocidad: +1
Wyvern Helm+1/Shura Zunari+1: +6
Spike Necklass: +3
Bushionomimi: +2
Vampire earring/Triumph Earring: +4/+2 (ok vamp is +4 but only active half the time, so take this as you will, i'd consider it str+2 since you can't always rely on it to macro in for ws)
Kirin's Osode: +10
Alky Bracers: +11
Flame Ringx2: +10
Forager's Mantle: +3
Warwolf Belt: +5
Shura Haidate +1: +6
Heroic Boots+1/Hmn Sune-Ate+1: +3
Combine that for a total of STR+67 with Triumph all the time or STR+65/69 if vampire earring is active. If i've missed something let me know.
Also in reply to kayoto i use byakko's in exp when i sub warrior due to the critical hits and Shura with thf sub. Also i cant explain but it seems like double attack kicks in more with dex, completely no base for this, just personal experience.