I don't really understand why you want to change from procedural to OO interface. If you don't have a good reason to switch, don't.

The general advise is to use a procedural interface when the functions in a module don't work on the same data.

If you have many subs sub1, sub2, ... in your module, and you call them all like sub1($data, @other_args); sub2($data, @other_args); it might be high time to pull $data into an object.

If not, simply stay where you are.