Not safe.
Max efficiency for the PSU is at 50% useage. It remains 'OK' at 80%. 450 * .8 = 360w. At 360w it will actually waste around 16-19% (converted to waste heat). At max draw it will deliver a maximum of 360watt (20% waste heat). You should never run a PSU over 80%. As the temps go up, efficiency will continue to drop. As dust gets inside, efficiency will drop. You will only get 360w if it is in a sealed and refrigerated room.
I would suggest at least a 550w, ideally a 650w one which is a good quality.
https://linustechtips.com/main/topic/631048-psu-tier-list-updated/
I have a bias towards Seasonsics.