After not seeing any replies, I tried to research your question. None of my Fisher Body, Firebird or Camaro documents and sources provided any help. The logic says that Body By Fisher would likely add the mountings for any GM car in 1968 (for evolving fed edicts in that timeframe). But logic does not always seem to apply to these cars.

I did find this video that may help. They seem to confirm that the answer about the probability and location of the mountings are a possibly, maybe, somewhere. They do show how to locate the mounts, if they exist, with minimal disassembly and damage.