I´m about to swap rockers from 1.5 to 1.6 ratio, does it affect to my spring load requirement?

It is a small block with MP .590" solid flat tappet and comp #978 springs with about 130lbs seat pressure and 360lbs open (if I remember correctly).

New rockers will provide .040" more lift but since the springs will be pressed that much more they will also provide about 16lbs more open pressure, is that adequate or do I need to shim them more or something?

those springs should be ok. check them all, and verify your installed height. check for coil bind, and so on, valve to piston clearance, everything. the safest way to approach a rocker ratio change is to look at it like a cam change. it changes everything, so check everything!