That's a shame about the inner arch sections. I'd never even heard of ziebart, I had to google it.
I've been dithering about a full boot floor panel but having looked it again, I think mine is a goner. Threads like yours make body work much less intimidating for the uninitiated like me, so thanks for writing all this up.
No problem . Ziebarting without doubt has kept the rust at bay but after 41 years its snuck in under the wire. Such is life, it could have been so much worse.