Anything's possible. Well, almost. But expect to pay a lot in lithium batteries to get a bus to get 100+ miles.
This is an estimation, but if a bus used somewhere around 1 kWh a mile, then you'd need two Tesla Roadster-sized packs to get it up to the 100 mile range mark. A large battery pack plus a range-extending generator setup might be more cost effective.
I'd recommend looking in the DIY electric car garage or www.evalbum.com and see what other large vehicles get out of their battery packs to get an idea.
I'd love to see you do it, but you'll need deep pockets mate!
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