Finally some time to update this blog. The engine is working - the reason it didn't start was that the distributor cap wasn't put on correctly.
Two other problems came up. The first was the joint where the fuel line joins the carb. This is different from the 2.4 mk II with the HD carbs. I couldn't find it in any parts manual.
I cut a new one from a piece of universal fuel hose that was an exact fit.
Then I found out one of the carbs was leaking through the overflow outlet. Turns out I put the little "valve" in backwards. This took two minutes to correct.
The leaky radiator was - quite to my surprise - fixed quite quickly with CRC radiator sealer (see this link). It's been leak-free for a couple of months right now, but of course there hasn't been any pressure or movement.