Hi and welcome to the forum! the car looks like an interesting project

as for your questions, hopefully the following will help:

1. as far as i know, you can use the early xr2i type alloy inlets, the inlet port is a slightly different shape on the later engines but i think it has been done before.

2. take a look at the exhaust manifolds (headers) here:

http://www.ashleycompetitionexhausts.com/manifolds.html

3. water rail kits to relocate the pipework and thermostat can be found here:

http://www.ikengineering.co.uk/#!pro...water-rail-kit

http://www.retro-ford.co.uk/shop/con...-manifold-z008

http://www.dunnellengines.com/zetec_...partno=RMP1952

http://www.raceline.co.uk/products/p...5&CategoryID=2

http://shop.autospeed.co.uk/zetec-en...ater-rail.html

some are cheaper than others. i have a retroford one, it's very well made and looks good too.