I have my 46 chevy pick up down to the bare frame getting ready to sand blast it.There are some ripples in the bottom of the frame rails at the rear of the frame from many years of being on a farm and being hung up and bottomed out on who knows what.My question is will it hurt to heat the frame up with a torch and straighten the rails out? They are not real bad ,but I would like to get them straight.Thanks for your advice