Earth, 2174

[Hai-Etlik]

You really would have been better off with something other than Equidistant Cylindrical. It's not particularly useful for a reference map like this, and it's just not all that attractive. Winkel Tripel would be my choice, but Robinson, Mollweide, Aitoff, or even good old Mercator would all work well

Having used it though, you should be careful about your map extent. A Normal Equidistant Cylindrical STOPS at 90° N and S but yours doesn't appear to do so. It's also kind of bad form (though not unprecedented) to have features extend outside the extent, or to have an extent with rounded corners. If you want rounded corners, it'd be better to have them on a neatline around the whole map layout.

You might also find a Desktop GIS handy for things like this. The editing tools are specifically designed for this kind of editing (Splitting shapes, merging shapes, editing mutual boundaries between shapes) and you can deal with projections easily. OpenJUMP, uDig, and QuantumGIS are all free and AFAIK can all export to SVG when you are done so you can finish up in Inkscape. On the downside, it's more software to learn (Unless you consider that an up side) and it's a rather different environment from graphics.