The tach cable from the 73-77 GT550 was the perfect length for the new speedo! (sorry I don't recall which post or who posted this info originally to give credit where it is due) I got it off FleaBay for $16.99 new with $4.95 shipping, but I did see a few used ones for less. Also picked up the Raptor petcock new for $24.50 including shipping. I ran the new cable along the same path as the clutch cable and there was plenty of room to spare.
Raptor was a breeze to instal, I touched up the paint on the frame under the gas tank since one of the previous owners must have had it off a number of times and didn't care about the stock petcock scratching the hell out of the paint
The Raptor cleared the frame with ease and turns much smoother then my stock one did also