68 Chevelle Wheels & Tires Concern, help!!

[BAMF68]

Hey guys, I have a 68 Chevelle SS Convertible that I want to change my wheel and tire package on. I want to go to a more of a pro touring look. Thinking about running 19" in the rear and 18" up front. The rear isn't tubbed and the lips aren't rolled. A particular set of wheels I was looking at was a 19x10 with a 8.45" backspacing and 18x8.5 with 6.72" backspacing..would that work? What's the biggest tire I could fit? Also I posted a pic of the car incase you have a wheel in mind that would look awesome, thanks!