340 ?

hi guys just bought a 340 pulling it apart and looking for info on the parts that i got the block i know is a 70 block the heads are j heads with 2.02 and 1.60 the crank number is 3751841 not sure if cast or steel the rods are 3418645 and the pistons are 2899479 are these the high comp or low comp thanks for any help