Have you check out carfax or autocheck? Did the current owner repair the car in his own shop? Did he purchase it for resale? How did the car get damaged? Was it a fender bender? Did he replace any suspension parts? How about the frame?
You need to know the detail of the repair. As far as the engine replacement goes, I wouldn't worry about it. Usually, the engine has a one year warrantee. If you have a chance, call up the Acura dealer and ask the service consultant or technician about the engine replacement and the condition of the vehicle. Ask a lot of questions !!
Take your time and make the right decision for you. Hope to see you with your new ride soon.