I’ll quote the Eclipse user manual just for fun “Keep the Eclipse well ventilated, dust-free, dry, and, like Little Bear’s porridge, neither too hot nor too cold.”
Personally, I give all of my vintage rack mount gear space in the racks if possible. These machines can be expensive and difficult to service, so my suggestion is to play it safe.
You could do a test with either machine in the smaller cases and see how much heat is being generated and make a decision based off that.
