I'm not exactly sure which properties you want to match. But create a variable for each one and set that variable to the current value. Then change the current value to the event value. Finally change it back to the saved value. For example:
 

            //save the current values
            int saveHeight = myVegas.Project.Video.Height;
            int saveWidth = myVegas.Project.Video.Width;
            double savePAR = myVegas.Project.Video.PixelAspectRatio;

            //Set the values to that of the desired event
            VideoEvent vEvent = (VideoEvent)evnt;
            VideoStream vs = (VideoStream)vEvent.ActiveTake.Media.Streams.GetItemByMediaType(MediaType.Video, vEvent.ActiveTake.StreamIndex);
            myVegas.Project.Video.Height = vs.Height;
            myVegas.Project.Video.Width = vs.Width;
            myVegas.Project.Video.PixelAspectRatio = vs.PixelAspectRatio;

            //Do the needed processing

            //Now reset them back
            myVegas.Project.Video.Height = saveHeight;
            myVegas.Project.Video.Width = saveWidth;
            myVegas.Project.Video.PixelAspectRatio = savePAR;