As far as i can tell, the Bosch GT40 coil was originally designed for a regular Kettering [points] type ignition. The suffix "R" means that it is intended for a system that uses a resistor.

If your car used a high energy ignition, then it uses a coil that is made for these systems. Don't bother using GT40R's to substitute for coils in a coil pack.

An auto sparks may be able to shed more light. Perhaps Phunkdoctaspock can add more or correct my info, as this area is his professional baileywick.