Dude its a difficult project. And I will second the opinion of of @KhakiMB. Go to Mandi Bhaudin. Not olny that U will get the parts there, U will aloso be able to find a project vehicle in a good price.
Dont think bout the merc G wagon. Coz the parts are difficult to find, apart from that a decient 1980s G wagon will cost U around 750K; only if you find one. So stick wid a defender project.