As a fan of r63, I would have to do it with my characters, sooner or later. Strangely, though, I started with my own ponisona, Overthough.
First, I needed to redraw him: my hair is not that 'blackpowerly', and my beard is far messier than in the other version.
Next, genderswap. I decided to keep my r63 with a bodytype similar to Lullaby, because it's cute, because short-chubby-fillies are awesome, and because my ponisona's flank would be too large to fit a normal weighted mare anyway. I gave her long curly hair, worn in a classical style, and some purple bangs - I'm sure my r63 would be excentric enough to dye random colours on her mane.
Finally, the name: while Thinktank is not a translation of Overthought by any means, it fits the overall idea of 'thinking in every possible way about something', and it specially fits her heavy constitution. She looks like a tank full of ideas, after all, and I think this is a good personality for her.
Instead of posting both characters, I decided to put both of them in a 'scene': it would be awkward to meet my r63, but besides the scientific sarcasm of both, I think we would have a great time together, heh.
Overthought, Thinktank and their Cutiemarks belong to me.
My Little Pony: Friendship is Magic belongs to Hasbro/Lauren Faust.