at 1275watts is it now ok to use something like a EVGA Gold G2 1300watt?
Been Eyeballing 1600watts ones but 1300 is liek 150$ cheaper

you'd be pushing it pretty hard.
easy solution is to underclock the S9 slightly, such as to 13TH - which would reduce your PSU load by 100W
Under clock a bit more to 11.5th. The 1300 g2 will work fine..
Then figure your math. You save 150 on the psu. But lose 2000gh to 2500th.