is it bad to go 0.40 over on a 400 the block is already 0.30 over but i have a set of new hyper flattop speed pro pistons and i wanted a fresh bore to make sure there was no damage in the walls

I see no issue with .040 over, you're only removing (at most) .005" of the cylinder wall.

ok thanx bud i just wanted to make sure!

mmmm i am not sure

I'd go .040" over with no real concern at all. Gregh's is .040" over. Rusts right. Now .060" over I'd want a closer look at the walls say with a sonic check.

I'd go .040" over with no real concern at all. Gregh's is .040" over. Rusts right. Now .060" over I'd want a closer look at the walls say with a sonic check.
thats what i kinda figured i sure enough dnt wanna go .60