[Kevin in NJ]

You are not measuring properly.

You need to do the string along the length of the frame.

Really, You want to take the little bit of time to do it right. It really is not hard to make your frame straight.

Especially with a pheaton body you want the best platform for the body. You will be spending way more time trying to get the body straight then then time it takes to level the frame.

Also consider the order at which you do things with the car. It is in your best interest that you blast and level the frame first. Then using a long straight edge, they are cheap at HD lowes, make the running board brackets level to the top of the frame and the holes square to factory running boards. This is actually easy to do. I bent mind cold with a pipe coupler and a long metal rod.

Then set up your front fender brackets and light bar. The light bar should look balanced and the bolts should go in easy at each end. Once the brackets are set up put on the running boards and splash apron and fit your front fenders. Any welding MUST be done on the frame and you need to keep the bead edge inline and verticle with the running board edge (I leveled the top of my frame to do this).

Once those parts are fitted you can move on with body repairs and alignment. Then take it all apart and start painting and building everything.

The restoration process goes better with that order and reduces time later in your build and you are not painting until after major fitting has been done.

That my thoughts take or leave it.