Got the engine started. That sensor went to the power steering so not crucial in getting it started. The fault was that the crank pulley on the Mazda engine was larger in diameter than the Ford pulley thus gave the crankshaft sensor a dodgy reading. All I had to do was swap the pulleys around, fabricate a new sensor holder to bring it closer to the pulley and she started up fine. However, as it would have it, the engine was making a rattling sound. A couple of garages diagnosed a big end fault so I currently have the sump off and am waiting for to fit new bearings as the crank doesn't look too badly scratched and a couple of bearings are a bitty scoured. Also the engine management light came on a couple of times the 70 odd miles I did on it - no idea what is causing that but hopefully will resolve:/
On a side note I have removed the crank balancer and replaces it with a delete kit which should allow it to rev a little freer and reduce weight by a good 15kg!

Other than that the engine fitted with no modifications - I put spacers under the OS engine mount to raise it up 20mm and had to modify the dip stick to fit behind the inlet manifold.