[blykins]

I would stay at least .120" thickness on a higher horsepower, high compression engine.

I doubt you'll have that with a .030" over 427. My guess is that it will come in at around .090".

If it were mine, I'd use it for something in a street application (if it still checks good for that) as 427 S/O blocks are getting harder and harder to come by everyday.

BTW, pay close attention to the thrust side of the piston.