i can't be quite as specific as you need david, but i'll tell you what i know.

i fitted a complete cosworth front suspension into a stock sierra, but that was including the crossmember and sterring rack (as well as hubs, lca's - normally called tca's on sierra's as they control the track, struts and anti-roll bar).

i would use a cosworth ARB as they are thicker (don't forget to get the bushes and chassis mount brackets with it as std ones will not fit due to the thickness). be careful with ARB's, as the 3 door one has a different length to later ones which affects the castor angles (some say for the good).