I love your build, great looking car. I know a thing or two about the 455 blocks from hanging out on v8buick.com. Lots of the guys on there agree that the stock Buick block becomes unstable over about 650hp. I don't know if I would throw a 150 shot at it myself but who knows until you try. A lot of the guys who are going 9xx and 10xx are doing so with girdled and filled blocks.....