A good electrical connection is more important than the length of the cable. We know this as Jaguar made a bigger spark by using a second coil mounted in parallel with the first. Initially this was with two coils on the tower but later the second coil was placed in the path of cool air at the front of the car by the radiator, so lead length per se at the coil side was not a problem. It may be more problematic for the pickup sensor (the W and G connections) as this is a low voltage signal. The unit also needs to be properly earthed as this is the discharge path for the negative side of the coil and also the reference for the input signal circuitry to the Fairchild chip inside the unit.
Extra heatsinking is very sensible.
If you want a graph of heatsoak versus time for these engines and what to do about it, this is covered in another forum thread in Solving heatsoak - a worked example
kind regards
Marek