Here's what Ogre did on his 58. He has a build page here, if you want to look. I like this idea, since the 54-59 trucks have very little kick over the rear axle. I may do something like this on my 54.
On the Anti-Dive thing... I don't think it'll be an issue. I did some calculating, dropping your rear 2" on a 116" wheelbase, comes up with less than 1 degree of difference. Here's a good explanation of Anti Dive.
http://performancetrends.com/Definitions/Anti-Dive.htm