20-40K lolololol if you are doing all the work your self mate it WILL be a lot less that that. 40k is just hilarious.

Your best bet is to buy a rusty cosworth 2-3K and steal the parts from that, or if you can't do it your self do what Muz said and buy the ready made version

IMO if you only wanted 300-350 brake and already had the rst and were going to do all the work your self and not rebuild the engine/box etcetc, you could do it for 5-7k

Rob,