So if I were to get something like this:
http://link.marktplaats.nl/270033813
Or this:
http://link.marktplaats.nl/269655773

Would that work?? Would that be easy to convert? I really don't know how this all works so if someone has a link to a DIY conversion site that'd be real helpful.

And why does the frame need horizontal dropouts? What's the problem with vertical ones?