You may want to talk to your Town / Township Inspector, or the Local Historical Society, or the Local Preservation Society, for leads on Home Inspectors that are VERY familiar with homes of that age (i.e., 120 years.) That way, you maximize your chances of getting a thorough inspection by someone who's qualified AND familiar with your type of home. Don't fret if you pay more than 'normal' because good advice comes at a 'higher price'. You see, you could possibly save a few $$$ now on the home inspection BUT end up paying 100s or 1000s more later on. In short, you get what you pay for.
You should perform your own walk through in advance of the Home Inspector where you'd make notes (on a per room basis) and present them to him/her. They should be able to give you an answer or at worst find it out. Also, a good Home Inspector should be able to give you an ESTIMATE for the cost of repairs / replacement / installs of what's not up to code (or whatever.) IF he happens to offer to do the work, REPORT HIM! (This is a conflict of interest.)
You're already on the right path. Just fine-tune it a little and you'll be able to sleep at night. My best to ya and hope this helps.