10 sec. 318?

Hi, newbie here. Which 318's-5.2's have nickle in the blocks ? I just got a Magnum-std. bore sonic tested ,and it was down to .102" between cyls. I'm thinkin .085" at .03" overbore is too shakey ,with 4" arm ?,(360/408).Story is, 71-74(360) blocks have thicker walls ? Currently building a 5.2L for a "light" car, about 2,400 lbs., steel crank,re-ground roller cam to mech. Edlebrock heads and dual plane. Would like to push max hp. to 7,000+ rpm. ? Thanks for the tech. ateam.