I think your converted SVG is probably very bloated from what it could be. I'm not sure if Inkscape will take it!
There are menu options such as "Convert to Text" but these do not necessarily work.
You can do search and replace on your file to remove references to default SVG attribute values such as..
stroke:#000000;
stroke-width:1px;
stroke-linecap:butt;
stroke-linejoin:miter;
stroke-opacity:1;
A lot of these are default anyway so search and replace with nothing for those.
Also it's amazing how you can reduce unnecessary precision. On your conversion for that particular file you might well find a decimal ending .0000001 or .99999675 all these repetitions can also be removed/reduced
