Wheel & Tire Size with a 3.5/5 Drop?

[Taylor21293]

I have a 1971 GMC C1500 Long bed, rear coil suspension. I’m looking into getting the ECE 3.5/5 Drop kit, but I’d like to run 20x8 smoothie wheels from Detroit Steel Wheels. I’m not quite sure if I could get away with running 20x9s, or if 20x8s will work. I’m also torn between what size tires I should go with. I definitely like the “low profile” look, but I’m not sure if a 40 profile tire will be too little. I appreciate any pictures/help with this!