Ive built 477 BBC engines but always used 6.385" BBC rods and had very good results
but keep in mind thats a 4.5" bore with a 3.75" ( 396 or 427 stroke)
the combo makes exceptional power PER CUBIC INCH OF DISPLACEMENT
but most guys opt for a 4.5" bore and a 4.25" stroke cranks as the resulting 540 BBC,
using off the shelf balanced components
you build has frequently had more torque and similar or just a bit more peak power in most cases