those #s are an indication as to how much you can bore out the block and still have sidewall.
they also tell us how much strength is there, #s that thick would tell me that cylinder deflection at Higher RPMs should not be an issue.
the #s for the block casting 5037471BF(early SRT392 block) that's in my truck are about .060 thinner, interesting thing is Cylinder #1 is .180 in the same spot as your .183 , and the .169 in #8 is .175 on my block.