my research indicated that there is no benefit of using a 205 block on a normally aspirated engine. In fact, the 205 block is unnecessarily heavier. However, I also found out that the 205 block seems to be able to accept a 93mm bore whereas that bore is very marginal on a standard block. If you are building a true 2.1 then that may require you to use a 205 unless you are stroking it in some way.
The experts will be along shortly to confirm or otherwise.