as above id get a 2l zetec

could also give a shot at head porting and manifold making if your feeling good

and as you say its just about the experience of building one im guessing trial and error wont be too much of an issue,

twin 45s go well on the zetec with a different ecu

personally id look at mk1 to mk4 escorts and mk1 to mk3 fiesta if it hasnt got to be rwd and find the one you like best (and is freeest of rust )