Not able to do automatic conversion of scripts from sql server 2008 to 2005

I have stored procedures created in sql server 2008 R2. Now, one of our clients is using Sql Server 2005, and scripts need to be converted to old version as there is syntax incompatibility like date is not supported in sql server 2005. Since the number of stored procedures is large, 364 in my case, doing it manually will take me days as I need to check for every supported/unsupported syntax.

What I tried :

I tried to generate scripts by setting option of Scripts for Sql version as 2005, but still scripts generated doesn't contain correct syntax as in case of replacing date with datetime.

Is there any other way, should Sql server not do it automatically!!