That bar is for a 73-76 A-body. You have a k-member that will work, but you need the correct lower control arms with the tabs in the proper place. You need LCA's that look like the first pic. You probably have ones like the second pic.
awsome thanks alot for the help. it makes sense now. ill see what i can do for lca i am going to do a bbp disc setup on the car aswell. so i might just get a setup with the neweer arms and solve the problem. thanks again