70 340 HP handling ability.

If the end goal is a 600+ hp engine I wouldn’t bother starting with a factory small block. Especially for the street. Spend mega bucks on a build only to leave a busted trail of parts behind you one day in the not so distant future.

You’re gonna need thousands and thousands of dollars in chassis and suspension upgrades too if you want to hook that thing up and not end up wrapped around a pole somewhere. So starting with a different engine or block shouldn’t be an issue.