Publishing/Copyrighting Shakespeare

Howdy everyone. First time caller in this forum...

So in 2002 I wrote and directed a script for "Macbeth" for my small community theatre company. Mostly this consisted of making cuts, reassigning lines to different characters, and doing a little gender-bending with the cast to create mostly the same story but with much different motivations than given in the original.

Now if someone else wanted to produce this version of the script (which I retitled to make it distinct from the original for my own sanity), what would be the best way to either A) publish it or B) at least "guarantee" I got credit as the creator (or I suppose co-creator...)?

I'm not worried about royalties or anything, just that my name goes on any PR/playbill/marketing if it were produced. Since this wasn't in New York or anything, I don't think the major playscript companies would even be interested in publishing it for theatrical use.

Does this look like a job for the copyright office and Lulu? If it matters, I do have an agent (for YA fiction) and book coming out from a Big 5 (are there still 5 big publishers...?)

Thanks!

The only other writer was Shakespeare. All I did was rearrange and/or trim things within the extant script. There was no contract, it was a labor of love for the company, nothing else.

I assume a Creative Commons license is easy to find and understand if I were to Google it? I've heard of them, but never really investigated what it was.

Thanks for the help!