Mopar LA small block progression:
First there was 273, it was bored out more and became the 318 (3.91"bore). Both have 3.31" stroke.
In '71, the 360 was a redesign with larger bore (4.00") and stroke (3.58")
In '72, the 340 came out (4.04" bore), and 3.31" stroke of the 318, however it used heavy duty rods which is why 318 and 340 cranks are different in balance. Early (71-74) 360 blocks used the same internal coring, allowing the block to be over-bored to 4.10", 75-up 360 blocks are thin-wall and this can't be done.
The 360 4bbl and some early 318's use the heavy 340 rods, unfortunately all these are all pressed in piston pins. Full-floating pins went away in '73. Only the '72 340 and 318l 4bbl engine used full-floating HD rods. All LA rods are 6.123", with the same pin and rod size, making interchange easy.
Changing from HD to LD or vice-versa requires rebalancing the engine.
All of this info is in the book: "How to rebuild your small-block mopar engine".
Additional:
The TA 340 uses the large bore of the street 340 (4.04"), was utilized in Trans-Am racing, were displacement limit was 5 liters (302C.I.). A special short stroke crank was used. These engines had special heads with offset rocker, allowing the intake ports to be opened up for better breathing needed at high revs. They competed with the Boss 302 in the Mustang and rare 302 used in the Camaro, and won many races.