If you are over 700 hp now, then you won't build any less on the next one, right? I would sell the stock block and go with a better one. I know that is not cheap, but when you figure the cost of a broken engine, and most likely a lost weekend and down time, and it gets a lot cheaper! On top of that, you would have options of a bigger bore. That almost always helps hp. Also You could buy the after market block, have everything but the bore and hone done to leave options open, and it wouldn't take long to put another together.