I think a 650w would be plenty even for a 350w Gpu as its not like the CPUs going to be pulling 200+w while gaming especially a ryzen CPU, cpu 100w Gpu 350w and 50w for the rest of the system.
you would get close as you need to factor in motherboard (vrm switching power loss), ram, drives, fans and water pumps all of that plus a cpu and the gpu could get up there or even surpass 650w.
my 3900x with a all core 4.4ghz clock can pull around 154-179w depending on what its doing, gaming is 150ish and under synthetic load it peaks 179w