Lightest engine and gearbox options

[Balidey]

As I thought it was about time I 'started' I am trying to get my plans together. One thing I want to do is (as per Mr Chapmans original concept) is to get the overall car as light as possible.
My thoughts were to use a Zetec engine, either 1.8 or 2.0. But which is lighter? Surely the 2.0 as the holes in the engine are bigger
But are there other engines to consider. I only want 'moderate' power so I could perhaps drop an engine size to loose weight, and maybe use foeced induction to make up for the loss of capacity. ie instead of a 2.0 how about a 1.6 s/charged, would that be lighter? Or do I go even smaller? What about the newer Ford engines, are they 1.4 Duratecs? S/charge or turbo one of those? There are hundreds about now.

Gearbox was originally going to be MT75, but again is the type9 lighter?

Rear diff. Something small and light. I have heard the Freelander diff is sometimes used, is that lighter compared to the Ford items?

I don't really want to go the BEC route, but the car is really going to be cut down to the basics. My friend has a Luego with an RV8 and massive alloys. And although its a nice car (which I helped build) its nothing like what a 7 should be. Its huge, heavy, thirsty and a bit too 'bling' for me. My car will be cheap, small, light, nimble, more fuel efficient. I'm thinking of using round tube for the chassis, making alloy skin seats as per the book, or possibly GRP seats. All the bare minimum.

So can you offer suggestions to a suitable power plant and drive train?