I reckon you could redevelop the Park End into a 3 tier and connect to the Main Stand and have lifts etc at the corner, take some of the facilities out of the main stand like the dressing rooms, the interview areas, the board room, that area for the players kids and family and move it all into the back of the new Park End, have the teams enter from there. Then refurbish the Main Stand using the reclaimed space for added corporate and catering. Let that be the new modern half of the stadium.
With the Street End and Bullens just slap and even more vintage look on it and keep it old worldie like one of them barn conversions that fella with the big head on More 4 does. The wife has Grand Designs on a continuous loop here, this one lad had a floating toilet set up in such a way that he could watch the mountains whilst taking a shyte. Glorious.