I happen to have a ripsaw with a 30" plate, and my wife has agreed we can downsize starting by listing our current home in Feb 2023. I am building a hardwood till now to hold all my saws, but I want it tall enough to hold any saw I might bring home in the future too. My top and bottom panels are s6s, my two side panels are s5s and tonight I had to figure out the length for the side panels.
TLDR: I come up with 38 1/16 inside case height to hold any 30" handsaw I can find dimensions for online. I am using 11" wide panels to make my case 11 inches deep. The perch rail for the long saws is 2 1/4 inches above the lower deck and 8.5 inches on center from the rear of the case. The comb is going to be a particulary well seasoned piece of Douglas Fir 2x4 with one half inch deep kerfs on the 3.5 inch face, the upper edge of the comb shall be 28" above the lower deck.
NB: future builders will need stock longer enough from (more than) 38 1/16 to allow for tails at each end, both ends, of the vertical panels. So 38 1/16 plus thickness of top panel plus thickness of floor panel = total panel length required for through dovetails.
There is a twist. I am going to use 4/4 stock for a French cleat on the back, but then also close the back with probably ship lap from 1/2 stock. When it is time to move I will be able to pack some paper around my well waxed saws, and then nail more shiplap up the front of the case and be ready to move house just like Mr. Jefferson's library. I have one inch of airspace all around so my saws don't get banged up.
There will eventually be a build thread. This thread is all about designing a reasonably efficient take on the standard galoot till that can easily hold any western handsaw an avid collector might find in their lifetime. When I posted my 30" rip saw here a couple years ago Pete Taran called it +/- 1860, and only the third saw he had ever seen with a 30" plate. 30 inch saws are in all the catalogues, but not common on rust hunts.
I will open with one picture of my trashy construction debris saw till. Long saws (30-28-26) go in the deep end on the left; shorter saws, 26-24-22-20 go on the right, above the storage area for files and spare nuts and so on. This isn't pretty, and it is starting to sag in the middle. However, it has been protecting my sharp saws and I will be able to recover some drywall screws from it as it transitions to the dump.
FWIW my circa 1860 Spear-Jackson is schooch taller here and a smidgen longer there blah blah compared to a golden age Disston D7 or D8. My dimensions in the TLDR paragraph should work for any normal saw up to a 30" plate. I don't collect misery whips, I do own a chainsaw. The 30" is on the very very far left.