You can, but the block would be near enough the only part you can use. If your going to all the effort of the build and sourcing the parts (Not to mention expense!) it's easier to buy one outright!

Plus no one has mentioned a turbo which is another expensive part, management, loom etc, this is before you get to tuning the chassis and modifying the drive train/brakes/suspension etc all of which is compulsory, as the standard components won't handle the power!

Basically you would need a donor Cosworth beside it to convert a lesser model, drive shafts etc, prop shaft etc are different, the standard hardware you have will simply not handle the extra power!

The above are just a few things that spring to mind, there are so many things that are different between the two!

Can you not import an engine/car from over here?

Martin