the frame sumtimes warpes when they weld it , you can bend it back in shape with some chains peices of metal tubing and a comealong if its bend to the side
you chain the chassis to a solid object then weld or clamp the tubing to the chassis mount the comalong to that and a solid object on the oposite side and start pulling little past where it needs to go then let the comealong back off and measure again
sumetimes you need a little heat to get the material to bend or stretch the right way
if it isnt a lot you can hide it by shimming the bed and the bumper , thats the only stuff afected by it if its all after the c notch
3/4 is abouuuut 1.5 to 2 cm...... yeah should be doable
if the frame is bend downward dril a bolt intoo a concrete floor chain the chassis to it behind the c notch and put an oiljack under the end of the frame and aply force untill youre either close or close enough , those frames can flex and bend every wish way you want it there not that tough