work up to it.. dont just have a crack you will need to get used to supporting teh weight, so over say 4 weeks after warmups,
start at 120 x 5 x 5
next week 130 x 3 x 5
next 140 x 2 x 4
next 145 x 1, 150 x 1, see how you are feeling,
next 150 x 1, more if you can...
get a spot, and be aware that 1rm efforts can really sap you
or do a few cycles of 5,3,1.