The amount of adjustable post length above the seat post collar is 180 with 170 recessed within the top tube. That is as low as it goes due to the asymmetrical rear wheel cutout. In order to go lower, it has to be cut. The question is how MUCH to cut. (DaveSSS is probably right by suggesting 10 mm at a time but I need a bike shop to do this for me and the only one who will is 20 min away. Annoying.) I don't really trust CompetitiveCyclist's calculator at this point. Wrench Science's calculator suggested 790 mm which sounds more accurate (a delta of 35 mm) and also what DaveSSS suggested.

I took some motion capture video and sent it to one of the prospective bike fitters. He thinks the 61 cm is appropriate (or that I could probably do a 58 cm with longer post/stem) but the saddle is too high. So I'll work with what I have for now.

Also, I spoke to a representative from CompetitiveCyclist. Admitted the calculator needs an overhaul and there have been complaints re: recommendations being way off. He advised me not to trust it. It is planned for an overhaul this year.