Wanting a 18x9f 18x10r wheel setup am I crazy?

mine are 17x8 with 5.72 backspace. i've installed a b body rear in it that currently gives me about an inch clearance to the springs and about the same on the outside. i'm hoping to go with 18x9 with around 6.20 backspace on the back, they should just barely fit, and 18x8 on the front with about the same bs that i have now.
i'm using drum brake spindles to work with my brake package on the front, but the disc spindles worked fine too.