Take Two. 
OK, so... here we go. Painting for dummies. I'm gonna detail the steps involved in painting. Here's the tank we're using. It has a single vacuum petcock on the left side, so 80 something Special? Inside is clean as a whistle. Maybe one or two very light spots of rust but no pitting. A few minor dings here and there but overall good and straight.
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Here's the bad. The existing paint.
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It goes on forever. At least 4 coats that I could see.... with prolly a quart of primer 'tween each coat. What a mess.

I've learned from experience that when it's this bad, stripper just turns it into a messy goo. So I drug out the 3" disks (#60) for the die grinder and went to town. This little bitty tank took about a dozen disks. With that aggressive a grit, as soon as I started to see metal, I stopped. Once it was down to the last layer, I switch to red rolok disks and took it all the way to metal.
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Too late tonight, so tomorrow I'll use some stripper to finish off the little nooks and crannies. At least now it'll be a manageable amount of goo.
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EDIT: All suggestions on different/better ways to do things are most welcome.
Bonus video: How to open a tank cap without a key.