360 block help thank you

No, you cannot if you use the 360 crank. The 340 pistons have a much taller compression height and will stick out of the block by over .150" if used on a 360 crank!

You can only put the smaller stroke of the 340/318 crank in if you you use the 340 rods + pistons. But, the main bearing diameters are smaller for that crank than the 360 crank mains. So you have to get what is essentially a shortened stroke 360 crank. I do believe that SCAT (or someone) makes that animal.

And then there is the matter of balance. Stock type 340 pistons are not even close to balancing with a 360 crank. There may be some lighter 340 pistons that will work out.. it has to be computed. But that does not solve the stroke and rod+ compression height issues as mentioned above.

The rods completely interchange and are the same rods.

Are you trying to re-use the old 340 pistons? Tell us what is the use/goal for this engine so we can perhaps help better with alternatives.