You could make it close to 60k by just not having the drop in the North stand as shown below, the south stand goes across all at the same height, no idea why they`ve done that.... That wouldnt affect intimacy etc.
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There was no space to go that far back in the North stand upper tier mate. That's why there's a drop. It's literally right up against the water plant (we've actually borrowed some of their land whilst we build the stadium)