Given below link explain How to host own git repository on Onedrive/Dropbox/GoogleDrive.
So in our case there will be server drive instead of Onedrive/Dropbox/GoogleDrive, I suggest we need to give a little hands on this approach and I feel it will work.

https://www.youtube.com/watch?v=qF9AEe2SJas

I find these link useful to understand GIT
some given links uses paid tool like CopSSH but I believe we will be able to do it free with GIT extension or GIT bash alone, just we have to try.

http://www.nubaria.com/en/blog/?p=633
http://www.codeproject.com/Articles/655560/Step-by-Step-Setup-Git-Server-on-Windows-with-Co
https://github.com/msysgit/msysgit/wiki/Setting-up-a-Git-server-on-Windows-using-Git-for-Windows-and-CopSSH

https://gitextensions.github.io/
http://git-extensions-documentation.readthedocs.org/en/latest/remote_feature.html
http://stackoverflow.com/questions/315911/git-for-beginners-the-definitive-practical-guide
https://lostechies.com/jasonmeridth/2009/06/01/git-for-windows-developers-git-series-part-1/

https://www.youtube.com/watch?v=zMz9IZjUBFM

I also attached a document of GIT extension. In this creating repository has shown.

Hi Aditya,

We need to consider below points for Git-

1. We should be able to give speparate access rights to folder per user.
2. Branching and Merging scenarios
3. Tortoise SVN to Git Migration with keeping history of old files as is.
4. Performance overhead verification if we can sustain with 200 users.

Let me know if you need any help on this.

Hi Vijendra

After going through many articles from Internet my conclusions are below:
1. We should be able to give separate access rights to folder per user.

• Yes we will be able to do it using SSH software like OpenSSH , Apache MINA , CopSSH. In this CopSSH is paid software. we can also try by applying windows group policy.

2. Branching and Merging scenarios

• For this lots of documents and examples are available on internet, I have downloaded some which I found Good. so It wont be a issue while handling GIT.

3. Tortoise SVN to Git Migration with keeping history of old files as is.

• Yes this is possible. I found number of articles doing so.

4. Performance overhead verification if we can sustain with 200 users.

• Well for this scenario every body has talked good about performance and management, but I nowhere found that How much Number of user can GIT handle.
  But I also find that Google , opera, nvidia like companies are using GIT with other repositories . So I feel it should fulfill our requirement.

PS: However these Information I collected from Internet, We need to give hands on to verify all solution to our scenarios to get maximum .

These are some Link:

For Performance
• http://git.661346.n2.nabble.com/Git-performance-results-on-a-large-repository-td7250867.html

Tortoise SVN to Git Migration with keeping history of old files as is.
• http://jonmaddox.com/2008/03/05/cleanly-migrate-your-subversion-repository-to-a-git-repository/
• http://stackoverflow.com/questions/79165/how-to-migrate-svn-repository-with-history-to-a-new-git-repository
• http://blokspeed.net/blog/2010/09/converting-from-subversion-to-git/
• https://www.kernel.org/pub/software/scm/git/docs/git-svn.html
• https://github.com/nirvdrum/svn2git#readme

Branching and Merging scenarios
• https://git-extensions-documentation.readthedocs.org/en/latest/index.html

Still I am looking for more, will keep you posted

POC for SVN migration to GIT is successfully completed.
GIT Lab successfully setup.
Demonstration for how to use with GIT with Git extension is done.

POC is done so long back.