Gas tank cleaning

I recently purchased a second-owner 1982 Honda SilverWing, that appears to not have run since 1988.
The first thing I discovered, of course, was the un-usable but in mint-condition fuel tank. I restored that tank using a home-made electrolysis system. The tank appeared to have been full when the bike was parked. To say it was bad is an understatement.
It took about a week, and multiple anodes were used. But the only cost was the salt I used, and the power to run the battery charger. It eliminated all the rust; but some charcoal-like substance remained which I had to chip off. IDK what that was, but likely it was clumped varnish.
The rusty water had to be changed every time the anode burned off, and new salt poured in, as the old stuff seemed to become less effective.
The biggest challenge was inserting the anode in such a way that it did not contact the metal tank.
It could have been faster, if I had run the charger non-stop. But I didn't want to run it un-attended, as it was my first time using this system.

But she's all ready now, for fresh gas, in spring!