Questions about Wheel/Tire/Shock Setup

I've been lurking for a while, trying to figure out an answer based on the "Largest tires" post, etc but figured I'd like a little confirmation of what I'm thinking. Here's the truck info:

2007 Double Cab Limited
1" Spacer in front
2" Block in back
20" +35 Ultra Goliath wheels
305/50/20 General Grabber AT2

I'm looking at getting new tires and replacing the suspension at the same time. I think the shocks are aftermarket, but I'm not 100% sure.

Here's pictures of how it's currently set up:

I only get rub at full lock when backing up on the front as you can see in the last picture, and barely any.

I like the way it looks now, so I don't want to change the lift any, just wouldn't mind having some "fatter" tires. I'd like to know your thoughts on what would happen if I tried to run 285/60 R20 tires. They're almost an inch narrower, but they're a decent amount taller than the 305's are. I'm wondering if the narrower 285 measurement would solve any issues that the higher sidewall would present.

Also, I know this is ""Wheels & Tires," but would it be better for me to get rid of the spacer in front and run 5100's all around? I figure the block would stay in the back, but I could get the front lift from the shock itself rather than the spacer and just leave the back shock at "stock" height.

Thanks in advance for your advice.

-J