[Psymon]

Well, this is interesting! A rather-knowledgeable friend of mine on Facebook pointed this out to me. Here's what he wrote...

You can indeed claim copyright. You did editorial work. This case is similar to what you did.

http://www.5rb.com/case/hyperion-records-ltd-v-sawkins/

Worth taking a look at this court case (if you can manage with all the legalese). This is a UK case, but nevertheless it still provides some "precedent" with regard to a case similar to my own. Obviously it wouldn't apply to simply publishing a public domain work "as is," without making any emendations to it, but I can see my friend's point that this is rather similar to what I've been doing with my book.

Any thoughts?