It is unfortunate to note that you and your HR Head both have not understood what Organisation Development (OD) is. OD is not a small project that can be given to HR Recruiter.
I recommend both of you to read books on Organisation Behaviour (OB). In all the OB books, you will find chapter on OD. You need to understand what OD is. It is not just restricted to organisational restructuring.
Since both of you do not have iota of understanding of OD, there is no point in giving our comments. About an year ago, I had given my reply on this subject. You may click the following link to refer it:
In addition to the above link, there is knowledge category called Organisation Development in this forum. Go through few threads in order to understand about OD.
OD do not necessarily call for any change in structure or hierarchy, it is all about doing all those essential activities that leads the company to a brand and beyond.
It will be like a Doctor trying to build Flyover.The problem lies with your HR head. Further, it appears that you people have a mindset that you know everything.If you are serious about, you can decide about the structural changes etc 7 have discussion with professionals with good track record.