to turn the 413 to the 440 via stroke, you needed new blocks, pistons, and rings. from a manufacturing standpoint, you needed a new core box for the block, as well as revising machining. you needed a new die cast mold and revised machining for the pistons. and new rings for the larger bore

to turn the 413 into the 440 via stroke (4.185" bore, 4" stroke) you needed a new crank and either pistons or rods.

if the base crank forging was done smartly, it could've just been a change in the machining setup with the same rough forging, no additional tooling required.

you'd have the same issue of a new mold and machining setup for pistons, or new tooling for a 1/8" shorter base forging for the rod....

from a procurement/material handling standpoint, you still had to create new part numbers and inventories for pistons, rings, and blocks, vs. pistons & crank.

thinking about it, I'm kinda suprised that chrysler didn't commonize piston and/or rods between the B&RB, and make up the deck height difference in stroke. or at the very least, when the 426 turned into the 440, the 383 didn't turn into a 396 (same bore), or for that matter, that they went to 400 cubes, which was a .020 overbore 440 bore....from a procurement/material handling standpoint, the part number/inventory reduction would have been significant.