After redistancing your rear forks a tool to check for parallel drop outs is easy to make and use. I use threaded rod very close to the rear axle diameter, cut it into two 10" pieces. You want the rods to be as big as will fit into the drop out slots. Thread on two nuts with fender washers on each rod. Install the rods on each drop out and tighten them down with the two nuts and washers. They should come together but not touch on the centerline of the bicycle. Trust me you will see any non parallel bends to your drop outs. Use the rods to bend the drop outs parallel. The rods should perfectly match and look like a single straight rod after you get done bending everything true. This can only be done on steel frames and drop outs. This is a simple cheap way to get good results with redistancing rear drop outs.