Are all 340 blocks the same?

There are very few race blocks left, don't even think they are being made any more. I read on Moparts there are 4 left and they are not siamesed.

There really is no difference between a 340 and 360 block strength wise, they are the same. Not sure where you came up with that? Different bore and mains, that's it. Same block.

How much power are you planning on that you are thinking of exceeding the limits of a factory block?