I've got 2500 miles on my 605hp 416 (340). I bag the crap out of it. Its a street car, no fill in the block. Machinist told me its the best 340 he's ever seen for minimal coreshift and thickness of cylinder walls. Its a '73 block. I am running billet main caps and stud girdle. I think up to 600hp isn't going to be a problem. Stay away from spraying it unless you want to really roll the dice. When I get closer to a rebuild or decide to try something different I think I will throw a 150 shot on it for ***** & giggles :) Of course there is going to be some risk when going with big power, but its minimal if built right in my opinion, I don't see a bunch of threads popping up about 600hp small blocks blowing up.
