Anyone interested in 83 Pace Arrow Tear down and Rebuild?

I would agree that 1 3/4" would be sufficient. Heat rises, after all. Make sure you secure the gas line to the counter in such a manner as it is impossible for it to contact the metal cooktop enclosure. I would be tempted to put a hard plastic sleeve of some sort there to prevent metal to metal contact. Just slightly paranoid when it comes to LP leaks.