Disagree since I have been there and done that and I’ll just say it outright so there’s no miss understanding…
Your wrong - Here’s why.
While the big block is heavier in stock form the only avenue I’d capitulate on and only to a degree since heavier leaf springs and T bars will greatly help this out, the big block can be very well equipped with aluminum save the short block unless a lightened crank & aluminum rods are OK with you. This can easily bring the weight down to a stock small block. While true! A small block can do the same, the weight loss isn’t as great but will be lighter. Your still behind on cubic inches.
I would not use the big block for carving corners but that’s not to say they can’t do well.
I’ve own and drive a 400/727/8-3/4 ‘71 Duster.
Also FWIW, I’m a small block nut.
Not so much on big blocks.