Rules on posting modified versions of plugins?

Here's the background:

I was recently in the Plugin Requests forum looking for a new project to take on, and found the

Updating the Turret Plugin​

thread, asking for an update for Turrets. The author had posted the plugin and not logged in since. At first I just recompiled it for 1.3.2's dependencies and posted it so people could use the plugin again. But then I decided to get into it and figure out ways to add some of the features people were looking for.
I've put in a decent amount of time and gotten some good new content for the plugin, and it seems doubtful the author is going to be back anytime soon, so what exactly are the rules about posting a new Turrets plugin so I can upload my new versions and have people actually see it? What kind of recognition do I need to give, is something like this even allowed, etc?
Any help would be awesome, because this plugin is way too cool of an idea not to get out there again

 

Show that the author hasn't logged in since he uploaded it. Show that you tried contacting him and he didn't respond. Give him credit. That's pretty much it.

 

Coolio, sounds reasonable. Thanks Tirelessly

 

If you where the author what would you want a dev to do if that dev took over your project after you left it?
If it where me, pretty much all i would request of you is to give me credit on the stuff i made and then you could take the rest of the credits for the stuff that you added or remade in plugin.