Yanis,
I would wait until you get the new junction block before you go any farther. Inside that red tube is a piston that all the cables fit into. They are all held in the piston by a tiny swage, about 2mm dia. I am not sure about the piston you now have, but the new one you have ordered has a small slot cut in the side of the piston that allows you to insert the cable and swage. and once the piston is in the tube, the cable can't come out. It works the same way that the cable hooks into the carb slide. If you can get the throttle cable out of your present junction block without cutting either end of the cable, It should go into the new block without trouble. The holes in the new end caps are just large enough to allow you to insert that small swage right through the cap and into the piston. If you assemble the cables in the junction block before you hook them up to the carbs or oil injection, you should have enough exposed inner cable to hook everything up. I think it will all be much clearer once you see the new junction block. You probably won,t have to do this, but at the very worst you may have to order an inner cable with a swage on one end and use it in the existing outer cable housing.
Bill.
