I agree on leaving it alone. It's 34 yrs old. I'd say you got more than the average life a water heater. If it were 10 yrs old, maybe clean, but it's working OK. 

Cleaning out the scale might lead to pinholes showing up in the bottom of the tank. Of course, it will start leaking profusely when you're not home. I'm guessing most water heaters fail due to leakage. You can put a pan around the bottom with a drain hose. But, that's like a spare tire on an airplane. Just doesn't get used much.

Then, about tomorrow, I'd start checking w/local plumber shop on new heater, installed price. The heater you replace this one with will probably outlive you....probably.