Not sure how your present ignition system is set up.
The 74 & later TR6 may already have a different coil such as the Lucas 15C6 & ignition system. This coil is made to be used with an external ballast. A "sport" coil might be substituted by bypassing the existing ballast. It's not likely that the conversion would produce noticeable gains on the later systems.
For use with points, a "sport" coil such as the Lucas DLB105 which is internally ballasted, has a primary resistance of around 2.6 ohms. The standard internally ballasted standard coil such as the Lucas HA12 has a primary resistance of about 3.1 ohms. The exact numbers will vary with the particular models of coils being compared.
The sport coil would draw about 18% more current through the points, give about 6% increase in available voltage & around 18% increase in spark energy. Many folks feel that the increased output offsets the somewhat shortened point life. There may be a slight benefit from opening the plug gaps .005" to .010".
In the end, you may notice slightly better starting & a little smoother running.
D