So you want to build a turbo a12 like others have said choose the car you want ....
forget the decomp plate theres no real need for it .Atleast use a a14 head on an a12 as the head flows better .
read through the tech section and learn how to lock the diizzy up save a lot of detonation problems later on in the tunning process..
Make your flange for the manifold and start with buying some steam pipe .You should be able to pick up a good working turbo for under 150 $ and su carbys are cheep as .you will need a electric fuel pump the turbo will lean out and probablly blow on you due to lack of fuel...I have a name of a company that has a program on there profile cutter for the a14 flanges if you want one done ..cheers