I don't know. He's got the right attitude and acting ability for Kincaid but I always pictured him looking about 35, with brown hair down to his shoulderblades and kind of predatory features. I don't recall how JB describes him in the books, though.
Page 107 of the Paperback edition of Death Masks:
"A man stood on my doorstep. He was nearly as tall as me but looked a lot more solid, with shoulders wide enough to make the loose black jacket he wore fit tightly on his upper arms. He wore a navy blue shirt and stood so that I could see the wrinkles caused by the straps of a shoulder rig. A black ball cap reined in dark golden hair that might have fallen to his shoulders. He hadn't shaved in a few days, and had a short, white scar below his mouth that highlighted the cleft in his chin. His eyes were grey-blue and empty of any expression in a way I had seldom seen."
^^^ Harry's description of Kincaid the first time he meets him. This description actually brings to mind Josh Holloway (Sawyer from LOST, the only character I frigging knew since I never watched the show). Although I hafta say, my favorite pick for this role is Christian Kane. He's just BAD ASS.