Emmissions???

[snapper]

Eddie99 on Locost builders has 2.0L Zetec in a seven and has a very neat/small cat in the pipe after the joint to the manifold. These cats are often seen at the kit car shows and are quite cheap.
You will be advised to fit the engine at this stage complete with standard injection system, fit a lambda sensor and check the emmissions. Getting round the Ford ECU security is very difficult and I find the Megasquirt a bit beyond me at this time, you may need to budget for an ECU and setup.