I'd try to fit in Improved Sneak Attack, and use a decent Str. Neither
max Int nor
All-out str/con are really attractive to me - the former needs a lot of gear to compensate the neglection of a to-hit stat, the latter is simply lacking decent assassinate dcs. I prefer a Str-based build which does not neglect Int and can take Improved Sneak Attack, i.e.
16 Str, +5 level up
17 Dex + 1 level up
14 Con
8 Wis
13 Int
8 Cha
This qualifies for ISA, and achieves 30 int (e.g 13 base + 2 capstone + 1 adaptability + 3 tome + 6 item + 1 except + 2 insight + 2 ship ), which is the sweet spot to me concerning Epic Midnight Greetings.
For feats, I'd go with (in no particular order): Toughness, Power Attack, TWF, ITWF, GTWF, IC:Slash, EWP:Khopesh, Precision, ISA, Hamstring (this can be swapped for OTWF, SF:UMD, or a useful PL).
Taking Precision and PA allows you some flexibility: Use Precision for EE Bosses with high fort and high AC, and use PA for everything else.