I'm about the same age (HS class of 74) and started riding a road bike a little over 2 years ago. I was coming from riding an old rigid mtn bike so figured it would take some time to get used to the riding position and it did take a while even with a bike with relaxed geometry.
Not sure how your current bike fits or how different a modern bike would be, but it seems like it would be worth trying a few to see. Depending on what your local shops carry, a Trek Domane, Specialized Roubaix, Cannondale Synapse, or similar would be worth taking for a test ride. On the other hand, if you're mainly just riding with your wife at a leisurely pace, maybe a flat bar road bike or hybrid makes more sense.
You can modify/upgrade your old bike but riding some new bikes might give you some ideas as to what upgrades would be most helpful.