These engine blocks are All water jacket. From what I have read, .060 over would be tops. There's plenty of bore to begin with anyhow so I'd be looking at stroking as much as possible. If not, find a bigger v6. There's an old story of a guy who hot rodded a 478 v6....made tons of power...more than enough to take on spiced out 454's. And it could handle 5000 rpm. The 478's have a 5.125 bore.
Also...in for the build. Be sure neat for sure.