Brett,
This isn't the answer you wanted, but it will keep the discussion going. The place that can build these is Kemp's Rod and Restoration, Inc. Hancock, Michgan (906)482-5656. I don't see that they currently build them, but they can basically build anything if they have an original piece for a pattern. From the photo, your quarter panels look like they would be fine for a pattern, but your challenge is to establish that these rear quarters fit not only your Meteor Hearse, but other models, and hopefully, other years. So, back to your original inquiry, can someone else measure theirs on other than a Hearse?
If you found they had wider application, you could probably convince Kemp's that they should go easy on you for the setup fee knowing that they'll be able to sell more in the future. From talking to them, most of the panels they can supply were originally produced for cars they were restoring or turning into rods.
Nice people to deal with, and their work is well built and fit just fine (rocker panels, tool tray and rear body panel).
Mark Lowery, CLC #25216
