buddha takes the place of krishna !! you are now talking 1300-1400 years ago
There is a series of miniature sculptures in tanjai big temple -which depict the story of shiva tripurantaka - shiva destroying the three cities ( not the famous mural but sculpture)...it is a kind of story board type of narration....without going into much detail - its depicts buddha in three of the reliefs....ie it actually shows buddha playing a part in that story / victory of shiva... which is 1000 years ago.
I believe that the Dasavatharam's have some message linked to them. Have put in a post in my blog about it. Please take a look and in my opinion Balarama fits in as an avataram more appropriately. Let me know your views on it too!