Upon reading https://github.com/schwern/gitpan/blob/master/README, I don't think it will because

If you tag your releases in a consistent manner and publish the location of your repository, gitpan doesn't offer anything new to the developer.

Gitpan is a read-only repository built from tarballs you uploaded to cpan, mostly useful to those who download from cpan :)

And if so, how would I push changes I've already made to my local repo to a local clone of a fork of a gitpan repository?

I don't think you need to, but I think this answers it

How can I merge gitPAN's history with my module?
------------------------------------------------

If you are the owner of a CPAN module and have an existing, but
incomplete, repository you can fill in the history using gitPAN. The
technique is outlined in this article.
http://use.perl.org/~schwern/journal/39974

In general, are there docs/tutorials describing work flows using github for managing perl distributions? I recall a lot of discussion around the time that gitpan got started, but am not having had much luck with search engines.

I haven't see one.

I've read Git for Computer Scientists,

I've seen A one-hour talk by Randal Schwartz describing what Git is, and why it should be used over other revision control systems,

and I've skimmed Git Magic a few times and Everyday GIT With 20 Commands Or So a few more times.

This has helped me muddle along, but I mostly work solo, don't publish much, and occasionally submit small patches anonymously.

I haven't had to resolve conflicts the git way, and I don't care much about attribution, I only care that the correct user name and email address are exposed in the logs, and not a history of computers i've used.