Why don't you do it on a small piece of paper first and see which you like better? I mean the tea staining vs. the detail, obviously you already have the map itself on a small scale. Also you'll be able to see if your ink will even work on tea-stained paper. Sometimes this stuff can be unpredictable.
Ok, if it's a felt tip, it SHOULDN'T run too much, but still, taking an hour or two to try it out on something else is way better than ruining your good paper.
I don't know how tea affects the longevity of paper, if that's important to you, it might be something for you to look up. I think slight acidity can damage paper over time, but we're talking decades and decades.
yeah good point. I mean I've done it before, I guess I;m just indecisive. I want the old school look of the tea stain but the vibrant colors of the painting and i cant think of a way to get the best of both worlds