Thank You Guys for your input , experience , and opinions !! This helps me to feel more confident in my own opinion that the stock main bolts will be fine in this application ! I did have concerns going back to my own previous experiences back in the eighties when I raced a 340 in a Duster . I was running heavy pop up pistons with a 12:5 to 1 compression ratio , huge cam , shifting at 7200 RPM , and crossing the line at 7200. with 4:88 gears . I had a problem with main cap walk on the center main until I used main studs . I was only worried with this street 418 because of the long stroke , but since the rotating assembly is lighter, the compression lower, and rpm much lower, I don't believe it will be under the load that 340 was !