Man, I do sympathize with you. I am 70 and don't have the energy I used to have. I control my BP with Losaratan and riding. No beta blockers. I refused. Beta blocker lowers max HR and force of contraction. If you ride enough over a long period of time there will be other changes in your aerobic system that can compensate. Increased red blood cell count and more stroke volume. It will take a new training regime to gradually get back there. You will have to slow down for some time as you get your distance back up.

You should check your blood pressure both on ride days and non ride days. If your BP is very low on ride days your dose may need adjusting. Work with your cardio guy. There may be a happy medium combining more than one drug. Maybe a beta blocker in lower dose combined with an ace inhibitor (that does not lower HR) may work better for you.