Perhaps it may be worth renting a bike to try it out for a few hrs. Don't know what options in terms of LBS in your area. Given that type of serious injury you did have and your chronic pain in relation to head positioning (which sounds serious), you really need to try certain bikes before purchasing.
Have you recently seen a physiotherapist for their advice/exercises? I know for myself, I must do all over stretching for back and neck on a regular basis, to relax my neck muscles, back, etc. No, I never had dropped handlebars and I've been riding for last 17 yrs.
At this time, I have no interest.

