Starting a Land Rover lightweight project

Morning all,
I can FINALLY start a project I've been day dreaming over for a while. My old man and I would really like to be able to get a lightweight and make it more fuel efficient. But before we start I had a few questions for you...

1. Is there any good reads/websites/shows etc to learn from?

2.Are there any different engines/modifications that can be used to increase the fuel efficiency. That's the main goal. Were not planning on turning it into a challenger or anything unrecongnisble... We just want to increase the fuel economy and get more mileage for our money...

I've heard whispering and rumours of 200tdi, intercoolers LPG, using disco gear boxes, Perkins prima engines and even using Audi 3 cylinder engines. Is there any truth in any of these? And were do I start?

Please don't reply with... "scrap it in and get a focus" "why get a two tonn brick if you want fuel economy" etc.

Thanks for you time folk.

If you have a good one sell it and let someone restore it to standard, what you are planning will devalue it. Buy a SWB S3 and improve that.

dont fit a tdi i did in one and it didnt improve it, a 2.5 petrol is what would suit it best

Thanks for the replys, we haven't bought anything yet as we're still planning what to do, need, ext.

Looks like we're scratching the tdi, thank you.