I'm trying to replace my rear shocks and the hardware is totally rusted!

Hey Guys, I have the car up in the air and was going to get these new shocks on. I have to lower bolts that have the torx bit. They are rusted enough that I cannot reuse them. Everything I look at online has the shock mounted side to side where my bolt goes back to front if you are standing in back of the car. I just picked up some shocks and springs from rock auto and didn't think of how bad the hardware would be.
Any advice would be appreciated. One online post advised just pulling pulling the torx bolt out and replacing it with a hex bolt, but I don't know what size I'd use.
Help!