Check out the splits last year...
I consider and .850 OPS the minimum you want in the heart of your order. That being said, this is a list of the over .850 OPS players we had (minus Dunn/Griffey) last season:
VS. LH
Phillips - .944
Encarnacion - .908
Keppinger - .901
Votto - .862
VS. RH
Votto - .880
Bruce - .869
I think we need a LH bat.