Well perfect.
I read again your post.
If the Super User is the author of the content, you cannot allow another user to see it until it is published.
To allow a particular group to see, here what you have to do :
MODEL (both item and collection) :
in the populateParams() function, you can see these types of initialization :
$item->params->set('access-view', true);
These inits are the individual ACL for the item in use.
You can add another rule ('access-group-view' for instance)
Write the code that correspond to this. (Try to find by yourself...)
You will be able to check them wherever in your component using :
if ($myObjectItem->params->get('access-group-view'))
{
...
}
But you can also do everyting in model, after the params init :
//propagate the rights automatically (for view)
if ($item->params->set('access-group-view'))
$item->params->set('access-view', true);
Do the same for edit, delete, ...
Hope I am clear.
Don't hesitate to ask if you don't understand.