Any of your 10 speeds will more then handle an idi. Your most common 10 speeds are twin shaft units and are rated for at least 1000 ft lbs, so an idi will be fine. There are 10 speeds out there that are "light duty" in the 6-800 ft lb rating, but they're rare to come across. Most MD stuff rated at sub 1000 ft lbs will be single countershaft units, in either 5,6,or 7 speed.
Your idi came with the sae2 housing when used in an IH. Those housings shouldn't be hard to find, neither should the flywheel. The problem you'll run into is a lot of your HD transmissions will actually be an sae 1 though, so finding a ten speed with an sae2 might prove difficult, even more if you want an OD unit.
Reading on the internet, a lot of guys have trouble shoehorning those transmissions between the frame rails, as they're pretty wide. You'll no doubt have to do some floor pan mods, or a pretty substantial body lift, to clear the sae housing. It's a lot bigger then the ford piece. The clutch set up can also get complicated, as they're usually mechanical linkages and in either a push or a pull arrangement.
My bus has an sae2 w/ sae3 adapter and an allison at545. The spare engine has an sae2 housing and I'm planning on mounting an allison mt6xx to it. There's a handful of threads on here where guys discuss md/hd trans swaps, but I don't know of any that actually got it accomplished.
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