How to hide blocks based on content type or for specific nodes?
The answer very much depends on how the nodes you want to show only bodies of are different from all other nodes of same content type.

I see two possible solutions:


Create a new content type and convert all the nodes you want to it. Then you can specify in blocks visibility settings not to show blocks on the nodes of that content type and create a new template for this content type in which only body is printed.  
Another way is to give the context module a try. The context module provides a much more flexible way to control blocks visibility so you can specify different contexts for your normal nodes (and assign blocks to this context) and your no-blocks nodes with no blocks assigned.


I'm sure there must be other ways to accomplish this, but these two are the first things I thought of :)