2406785 = part number ('59-'71 318 "A"/"LA" & '64-'69 273 "LA")
floating pin
* 1618699 = forging number
* 2406872 = forging number

2899495 = part number ('68-'73 340 "LA" & '72-early'73 318 "LA")
floating pin
* 2899496 = forging number

2899061 = part number (late'73-'80 360 "LA" & late'73-'80 318 "LA")
pressed pin
* 3418645 = forging number

I also found reference to this part number, but it overlaps the above info?:
3751015 = part number ('71-'76 360 "LA" & late'73-'76 318 "LA")

so, if I WANT to build an authentic 1970 340 engine with "correct" vintage rebuilt/remanufactured/restored parts/components - the 2899495/2899496 rod is the ONLY correct rod?

I understand there are cheaper/newer/stronger modern rods - but I WANT a 1970 340 engine

some charts show a .100" "offset" on the 340 floating rods, what/where is this dimension?

Want to go really nuts? When we had to use OE rods in our Super Stock 340's way back when there were different foundries producing floating rods. I can not for the life on me remember the markings, same casting numbers though, but these were lighter than the ones from the other manufacturer. I think it was 15 or 20 grams lighter.

2899496 = forging number This rod can be in a press pin fit or floating pin configuration. Only difference is a bushing in the small end. The 340s used the floating pin style rod.

The 0.100" offset is in the piston, not the rod. This offset was to reduce piston slap (rattle) when the engine was cold. Old trick was to swap pistons from one bank to the other to reduce friction drag for racing.

The early 318 rods were lighter but had a floating pin. 318 rods were 726 grams vs the 340 at 758 grams.

So, the '70 340 would use the 2899496 rod with bushed small end for floating pin.