I have experience in similar configurations (Apache, PHP, DNS (Bind), Mail (MTA: Postfix with Amavis - Spamassasin, and IMAP/POP3 with Cyrus), MySQL and more):
3 days of server configuration.
1 day of test by the client (you).
1 day of analysis of the applications that need porting and, if needed, cost recalculation or direct port.