1971 ( 340 ) Block & Crank obtained !

You have to over stroke any hole you are honing. If you don't, they get wide in the middle and tight at the top and bottom.

For what the OP is doing, he needs the dingle berry style brush rather than a rigid hone. He just needs to make sure the lifters can rotate in the bore.

Hopefully the OP is tubing both blocks. There is no reason not to do it.

Right. That's why I really like the old school dingleberry hones. They really have their place. I just cleaned up two 396 blocks that weren't as rusty as the OP's 340, but they were on the way. They both cleaned up good enough to use as is and standard, but one was cracked in three places. The other I am building.