Shortblock usually refers to complete bottom end and longblock complete with head.... I was just assuming that you where talking about an already built bottom end. while you can change the compression ratio a lot with the head obviously if you want to run NA you dont want the same 8.5:1 pistons that you would have for turbo. If your gonna spend the $$$ on a block thought why not check out Spoon? Endyn? JG has a huge turnaround time if you last name isnt LAM or Papadakis or any of the other big names. If I where going to get a block I would go with a nice B20 prepped by endyn that has been destroked using the 1.7 crank and custom rods/pistons. This is for Na of course but this setup could yield nice results with a turbo.