I'm not really familiar with the R50, so I can't tell exactly what I'm looking at in the pic, but if you are replacing everything, you don't necessarily need to get the nuts loose? Just cut out some of them... but if they are going into a part you are keeping then yeah, you have to get them out. Heat might work, but I don't recall if I've ever used heat on a brake system before... not sure what would happen with the brake fluid...
Maybe try to cut the piece you are working on out and attack it on the workbench, could be easier, but you might have to replace more lines...