The lower hose on all (?) small blocks is 1.75" ID. The lower hose on slant six's (all?) is 1.5"D.
The heater hose on my slant, SB, and BB are 5/8"D. Ditto for my Mercedes 300D's and minivans.
Not sure why you want to use those "Corbin clamps". I suspect most use them just to look original. Otherwise, I think they are inferior and only used for speed at the factory. Chrysler used those (flat style) on the power steering cooler on my T&C, which was a tow package upgrade (stealer installed?). Mine leaked, as it did for most owners. Indeed mine shot a spray up at my pump way above, so I thought that was the source and spent a lot replacing it.
I would think stainless steel screw clamps would look best and be superior. Even nicer would be the upgraded type with a smooth 360 surface and an outside clamp bolt, as used in "fuel injection" clamps and turbocharger intakes.