Information on a 340 for my 69 dart

If you don't have any luck finding an actual 340 block that is usable, you can use a 360 block to make a 340 cubic inch motor. You would need to buy main bearing spacers, use a 340 crank along with the spacers, bore it to 4.040 and buy a set of KB243 pistons. I'm pretty sure a member here built a 340 CI motor using that method several years back.