fitech base timing

i have the fitech 1200PA on a 410 sb with S475 turbo. fitech will be controlling timing. msd pro billet and digital 6al. cam is 254/260@50, 560/560 lift, 115 lsa. looking at 18 psi boost. my question is i'm not sure what to set base timing at if someone can point me in the right direction here. cheers