Hi Daz, and welcome. That looks like it's got loads of potential once you get it up and running! The following is general engine advice which works on just about anything. I can't be more specific cos I don't have a TC so don't know what things like timing marks look like on them, but a Haynes manual is invaluable for those little details.
A non-starting engine can be about the most frustrating starting point possible but it doesn't have
to be if you approach it logically. All an engine needs to run is some compression (not a huge amount), about the right amount of fuel and a spark at (about) the right time to light it. Given those three it will
run, even if badly, and from then on it's a lot easier to diagnose any remaining problems. So tackle each of those areas one at a time.
You already have a spark which is a good starting point. Is it a nice "fat" one at the plugs or a weedy "can just about see it" one? If it's there but weak then you need to check through the ignition wiring for voltage drops. A multi-meter is useful here but at least make sure all the connections are clean and tight. Do these have a ballasted coil? If they do, are you getting the full 12v feed when the starter's engaged? It sounds like you've already made sure the plug leads are in the right order so, once you've got a nice fat spark, use the Haynes manual instructions to set the static ignition timing. You've then got one of the three essentials for a working engine.
Next concentrate on fuel. Is the pump actually delivering any from the tank? Disconnect the inlet to the carbs and drop it into a jar. Crank the engine over and see if fuel is being delivered. If there's none then you're looking at fuel pipes, the pump or an empty tank (wouldn't be the first time
If you've got fuel to that point then open up the float chambers on the carbs and see if it's getting through the float valves. If it's not then check the valves and floats (are they stuck or leaking or sinking?) Once you know that fuel's getting into the float chambers there's really not much else to go wrong with an SU as far as just starting an engine is concerned.
So on to compression. This is a bit trickier without a compression gauge (about 20 quid from Halfrauds) but you gan get an idea by pulling all the plugs then replacing one at a time (individually), cranking the engine between each plug. If there's any meaningful compression you'll hear the cranking speed drop noticeably as the cylinder with the plug in is on its compression stroke.
If there seems to be a problem here then check the valve clearances to make sure you haven't got one valve not closing fully and, if that doesn't sort it, you really need to get hold of a compression gauge to see what each cylinder is reading.
Finally, if all that seems ok, but it still won't fire, then get a tin of Easi-start (or Start Ya b'stard if they're selling it near you
) and give a quick squirt into each carb inlet. That should at least make her fire, if not continue running. If she starts and runs at this point then you have a running engine which is a lot
easier to fault find. If she fires but doesn't keep running then re-check the fuel system.