I'm having difficulty visualizing how tearing out and replacing the east side will help that stadium at all. You still end up with a track, and a bowl that's too big and too far away from the field because of the track, but now the stadium would be mismatched, too.
Best option would be to demolish the entire stadium and start over, but I guess that won't happen. Next best option would be to excavate and lower the entire field by 10-15 feet, eliminate the track, extend seating down to the new field level, demolish the existing west side grandstands and press box and replace with a new press box. It could even be done is phases as long as you close off the west side grandstands to offset for all the new lower-level seating.