o.k people

So i went with the 4 bolt block for ease of getting it home and more space in the garage. The next step is a rotating assembly. I called my speed shop today and he gave me a price on an eagle assembly but the only thing i dont like to much is the pistons. They are 10.3-1 and i have always thought blower motors to be lower compression motors. Am I right or will i get away with 10.3-1 compression? I should say to, that the r/a is to build a 498 motor. One other thing i should ask( because i forgot to ask my guy today) was ...does the block need to be ground to clear the 4.25 crank?