k-frame holes dont line up

That's a tough one, that boulder must have been a monster. For a quick fix I would weld some pieces of 1/4" angle iron to the bottom of the frame rails about 3" long as close as possible to the rear mounting holes leaving just enough clearance to put the k frame in. Drill 5/8 " holes in the angle iron and then use the all thread mentioned above. Drill those hiles before you weld them on would be easier. Those rails will move a lot easier than you think. When it gets close to where the k frame bolts line up back off on the all thread, duplicate so when you back off the all thread the holes line up with no tension an the all thread. Cut out angle iron, bolt in K frame in and go!