I've had plenty of experiance with FPE breakers since they were really popular here in the Mountain State because they were so cheap, note I didn't say inexpensive.
No electrician I have met has had anything positive to say about the stab lock breakers. However, I've never seen or heard of any complaints about the large frame circuit breakers that were usually bolted to the bus. I've run across a few of these installations & the breakers appear to be well made.
I don't think you'll ever get enough data on the FPE stuff to help you out. You'll probably have to count on the Siemans equipment to do it for you.
I don't know how many years back 380-7 goes, maybe you could make a plea that this is unsafe & should be brought up to modern standards.
Good luck, I wouldn't touch this job with a 10' hotstick.
