I had 4.500 crank and 6.535 BBC rods at one time, for a 400 block. Pistons were 1.190 flattops, very light.
Crank had center counterweights, all the counterweights were cut back in their center areas for clearance at BDC.
It had some Mallory metal in it, but I never did a final balance.
I don't know how different a 383 block is in the crankbox area, compared to a 400.