What pistons do I have?

Ok, I know they are Keith Black, they are mostly flat tops, with valve reliefs. Anyone familiar with these? Are they any good (these are newer, so condition wise, I know they are good) for power/ mild build? I will be using 452 heads, and either a Comp Camps XE268H or XE275H, I think. I am open to suggestions on that as well. I pulled them out of my 383, I didn't find any oversize markings on them , but there is a "40" stamped under the piston (I tried to get a picture of it). Also, lots of room between top and second ring.
Thanks.
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