CA18 will go on without too much trouble as they are front sump like the cortina. When you say coilovers in the rear I presume you mean to 4 link the rear while doing so? You will have to adapt an escort kit. There are quite a few running ca's now. Have a qick google search, Will probably bring you to mk1 cortina . com. Plenty of pics and info there.
You will need custom engine mounts. Remove the inner strengthners on the cortina shell. Custom gearbox mounts. Cstom tail shaft. Need to run hi psi fuel lines, and pump, need a return in the tank or t to the filler. Cooler needs mounts, and space to run pipework.
Shaun
'If I'd asked what people had wanted, they'd have said faster horses....' Henry Ford