Max Torque/HP 4.840 Bore Space ?

I know the world has moved now to 5.00, 5.300, 5.500 bore spacing, and no doubt someone in the world has probably moved on to like 5.750 or 6.00.

Back to 4.840 for a minute (standard BBC), with a 4.400-4.500 ish bore, what's the most that's been squeezed from this combo with any semblance of reliability?

Just curious if anyone had any thoughts or observations/recollections?

Thx.