I agree with Richard. Effective age is what is most important, and that's typically not a real big adjustment factor.
I have had homes that were older, and did not know the exact age. I would put 50+, or 100+, etc, but I would pay particular attention to things that affect the effective age.
In my area, you can have a 100 year old home with central heat and air conditioning, granite countertops, jacuzzi tubs, thermal windows, insulation in the walls, etc. Chronologically it's still 100 years old, but effectively...........??
Rick