13:1 Compression Pistons in 340 Small Block

4spdragtop said
Why build or spec an engine around "leftovers"? Although those are cool.

Because he has the parts. I agree he could go a different route, but at what cost. The J heads and his 340 block will work with those Pistons. He could build it and use e85 without a problem.
Again it depends. IMHO