yea mate you can use the original pipes, and your so lucky you have a fuel return my vtr didnt have one so i had to block it off
the engine will only work if they are in the right way round because i put my supply line in to the return port on the fuel rail and it dint work so i took it off put it on to the other port and it worked straight away but because i didn't have a return pipe i was pissing out fuel lol so i had to get a length of pipe and shove a massive bolt down it covered in tiger seal lol