I'd avoid getting too close to the actual historical facts or common speculation of some of the stuff you're considering. It would let players who may know more than you get ahead of the curve you're trying to set as your scenarios unwind.
For instance, a lot of people would know about various speculatory writings about the Jack the Ripper killings...but if you just use those as pure rumor and change it up to your own mystery, you'll keep them off balance and let them have the joy discovery of the real killer, instead of them figuring out your plot ahead of time.
So, in the case of the Ripper, instead of what anyone may have read, you could have the killings be the result of a killer who was trying some Lovecraftian rituals, erred, and simply went mad...
or he could have succeeded, been killed, and the creature he summoned is doing the evil work...
...or it could be the result of a Necromantic cult, and to do the ritual killings, the slayers must wear a particular set of clothes and use a specific knife.
...or an Unseelie Fey Lord, outraged at what industrialized London did to his grove while he was away in the Unseelie Court, is going on a killing spree to scare humans away.
Etc.
Additionally, once you get your setting fleshed out, you can drop in familiar storylines and tropes from other eras or regions and tweek them to fit the campaign era.
For example, in my campaign, I adapted James Bond plots for my superheroic PCs to wander around in- they never suspected that the Archimedian Mirror Heat Ray controlled by a stolen Babbage engine was lifted from Man with the Golden Gun...even though I set the adventure in the seas off of China, just like the original.
They never suspected that the guy who could animate a giant, multi-armed statue of Kali was an amalgam of Japanese Mecha and a Sinbad movie.
And so forth.