Did they also open up the ejection port?

[email protected] said
Yes it looks very stock but it has been opened  

Unfortunately, reaming the chamber to 2-3/4″ and opening up the ejection port have a negative impact on the “collector” value of the gun, as it is no longer factory original.  From a shooter’s perspective, it is a plus, as the gun can be safely used with modern shells (though steel shot loaded shells is not recommended if it has Full choke barrel).  In regards to your question “how bad does it hurt the value?” that can only be answered by the perspective buyer.  From my own perspective, if it is a standard (Field grade) gun, in typical used condition, the reamed chamber and opened up ejection port will not hurt its value.  If it is a high condition gun, or something other that a Field grade gun, the alteration will put at least a 25% dent in the value.

Bert