Anybody run a 400 big block with a stock bottom end?

My dad runs a 400 in his Challenger, built back in the 80s. Stock cast pistons and stock rods with a forged 383 crank. The heads and block have been milled _a_lot_...no idea how much, I'll have to ask. Home ported iron heads with 2.08/1.74 valves (I think). Last I knew, he was running the 292/.509 Purple Shaft with cranking compression at 180-185.

Pushes the Challenger to low-12s. With near-perfect conditions, it should run high-11s.

Regularly spun to 6500 and has been run to 7000 more than a few times.

ROCK SOLID. He's been running it like this for as long as I can remember, 20+ years. It's been apart twice to check out clearances.