I haven't cycled the route in question. However the route between Albunuelas and Jayena is well used and looks straight forward with no risk of getting lost. If you want to get a good idea of the terrain you would have to cross in Spain use the VISOR/Sigpac
maps. Excellent for plotting routes which are not apparent on road atlases. You can use the maps and see the aerials separately or superimpose them together. The detail is fantastic and all the information regarding contours, spot heights makes it clear how much you will have to climb in the mountains.
Just click on page to open and drag map to center cusor over place or area you are interested in and zoom in. You get only the maps to start with and then the aerials come in at the larger scales. Tick imagenes to display ariels (ortofotos) or maps as required. The site also gives co-ordinates which you may be able to use with GPS, but I don't understand or use one. Too old!
Using google maps the one end of the track can be seen at the Jayena end
and shows it as an unsurfaced route. Should be alright in the dry, but if wet may get a bit sticky.