It is possible with 400's and the best efforts to leak down one a number of times and get a number of different results because the cylinders do move quite a bit.The logic behind aftermarket blocks is the failure of the OEM stuff.When you start talking about 550 hp,there is a formula for dollars spent per each 1 hp.So it as always comes down to your budget.

I knew of a guy with a 406 in a Super Gas car.It had a cast crank,high stall convertor and tranny brake.He along with all of us called that a grenade with the pin pulled on each run.If it wasn't for fact he couldn't afford anything else at that point,he won't have tried that.Got to the end of the season and tore it down.Bottom end was trash.If your thinking of a big time spray on this,I suggest to limit that.