I don't know their policy - you could call them up and ASK - but doubt they would care if you changed the sights. Monkeying around with the action to change safeties might be a different matter.
An extended slide stop is not a good idea, period. If you feel you just must, be prepared to take it off when you start getting unexplained slidelocks when not empty. Actually, an ambidextrous safety is not a good idea unless you are lefthanded and require it to get the gun going. The ambis are not as strong as standard.