The pit calc is the bible. I'd run with the numbers. If you veer to far from the answers, you'll be chasing your tail to get your temps right.
Put 3 shelves in. It's easier to do now then wish you'd done it. If one gets in the way while cooking bigger pieces of meat, pull it out. Hope this helps.
Current Smokers: Junk Char Griller, Mini UDS (Hydrant build), UDS (Bud Select can)
As SFF stated, follow what the pic calc says. As far as the shelves, I would go with three. It will come in handy when you do something thin like ribs but can be removed for thicker cuts of meat.
Take a tape measure to the meat department at your favorite grocery store. I think you'll find the 6.5 inch gap to be too small.
More like a pair of 8" would do a better job for you when cooking butts and brisket. 2 - 8's equals 16 (17 with gate thickness) then divided by 3 will give you 3 - 5's more or less which would be fine for ribs and the like. You can also put in the top and bottom only and do a whole turkey on the bottom with a rack deep enough for a pan of stuffing on the top.
And on the eighth day God created barbecue …. because he DOES love us and he wants us to be happy.
Current smokers: Egor (trailered RF) and Easybake (tabletop pellet drive)
Your CC is 24" x 20" and 32"H? That's more of a vertical smoker. The typical RF calculations may not apply. Why not a straight vertical with the FB directly underneath?
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