305 is still a ton of tire, and in the "looks" department the additional sidewall will change of going from a ~25.6" tall tire to a ~27.8" tall tire will the look a lot more than the 10mm of width.
In the front you may want to be careful adding any additional height. Not sure what you have on there now, but based on your picture it looks like your front wheels are lacking backspace as well. Making the front tire taller might have a real negative effect on your fender clearance. 26" is about as tall as you can go in the front anyway, unless you're running a really narrow tire tucked way back in the well.
In the long run, I think I would strongly consider going to a custom offset wheel. That narrow rear end really only suits the kind of wheels you find in 15" diameters, and with a handling set up you're not going to find wheels or tires that suit your purposes. You're already running drag radials, which aren't ideal for a handling set up. There are a bunch of options in the 335/30/18 size, an 18x12 would work great for that. But off the shelf you're not going to find an 18x12 in anything less than a 0 offset, and +20 or more is much more common.
The only real other option is a different width rear end. If you wanted to run an 18x12 +20, for example, you'd want your rear axle width around 56.75" WMS-WMS. If I remember correctly, that's almost exactly the width of an 8.8 with two "short side" axles.
