Used to Classic Trial a Singer Chamois Sport ( the rarest type Imp) so I have always used Hillman/Sunbeam Imp SPORT cables on my Class 8 Freestyle, their easily long enough, fairly heavy duty, so they last, and readily available....Run them down the top rail, under the pipe/rail/finisher thingy...
Think the last one I had was about £15.00, never had to fit a second since...... Get mine from Malcolm Anderson, THE Imp man, luckily a mile from where I live! He's friendly, does rapid mail order, phone him on 01823 350360, say Jon Way recommended him.....