Coil Getting hot

Is the visible spark, at the plugs, a pure blue plasma, or are you seeing any yellow-orange color to it? Assuming it's a good quality blue spark, then I'm not certain your non-starting issue is related to the coil.
What's important to keep in mind when using aftermarket, externaly ballasted coils is that you have the correct ballast resister, so that you're not overheating the primary side of the coil. Most stock plug wires won't handle high intensity, 50K+ volt coil outputs, and normal compression Land Rover V8 engines don't get much added benfit from using these. I don't find any issue with using stock Lucas coils on these engines.
Sometimes it's worth just clearing the decks and getting back to basics. I believe the later Land Rover distributors which use Hall Effect pickup coils instead of points and condensers, and the correct 'amplifier' (a missnomer, as it's just an electronic switch to handle the coil primary circuit current) very reliable. Additionally, the firing pulse is very precise, as opposed to a the wider, less precise firing from mechanical points. If you don't have this distributor, with amp, you can probably get a good used one from Paul Grant.
The longer you try starting a nonfiring engine, the more likely you will foul even new plugs.
Other items to check are your cap and rotor. Rotors can frequently be cracked internally allowing a spark path through the center, to the distributor shaft.