reformatting a postscript file from letter to a4 paper size ?

[shaulk@israsrv.net.il (shaul)]

I am getting a very narrow, practically none, right margin for the ps files of 
 ftp://athos.rutgers.edu/runet/tcp-ip-intro.ps and 
ftp://athos.rutgers.edu/runet/tcp-ip-admin.ps. (those files are recommended by 
the NET3-HOWTO as an introductory text.)
The very narrow margin are created both by gv and when printing the files.
Can it be that this is due to a letter vs a4 paper size ?

Can I change the postscript files (and not the source file) so that it will 
have a reasonable setting on a a4 paper ?