Replace with bolts and remove studs???

Standard thread...no left hand threads on these.

also if you have access to a welder, you can just weld the nuts to the stud by taking and backing the nut until the stud is just under an 1/8 inside the top of the nut and welding the top part of the nut to stud if you dont plan on keeping the nuts and studs for later use and using a ratchet or impact to pull them out