Chganging the revision numbers

I need to change the revision numbers for one of the project which is in SVN, it has 600 revisions, Now i want to rename the revisons 550 to 600 by some different revision numbers i mean like 801 to 850

so that my log should show from revision 1 to 550, and then 801 to 850.

In the remaining revisions i need to load with svn dump file.

How can i do this, this is in windows server