Another visit from Dr Johnson this weekend and we got the new engine started!  Not a very complex process really, just took a bit of faffing about with the electrics.

Adding some fuel
A collection of batteries
Initially we tried starting the engine with jump leads and batteries on the floor.  The starter really struggled with one battery so we added another in parallel:  no better!  In the end, Dr J bolted a battery into the proper place and used the existing battery connections.  Amazing how much of a difference the jump leads were making!
Bit of smoke from the DIY exhaust.  Tightening the bolts later fixed the leak
The main positive feed for the 24v system was on the starter solenoid which is no longer needed, so I made a plastic block to mount things on instead.  This saves a lot of wiring and keeps thing neat.
Most people use the series alternator mounting to mount the alternator using the same belt as the crank and water pump.  My old engine had a massive military generator mounting instead, so I had to make my own alternator bracket.
The alternator mount.
There are a few jobs left to do - leaky fuel pipes being one - but things are looking good for getting The Duke back on the road soon!