Hi, welcome, great project.

There are supplier/manufacturers in the uk that make custom thermostat relocation water rails and other parts for the fitting of zetec engines into rwd applications. I believe retro ford are one, I will see if I can find a link for you. http://www.retro-ford.co.uk/shop/con...-manifold-z008

To my knowledge the inlet manifolds are interchangeable between silvertop and blacktop engines so you could possibly go down that route.