i've got a AE86 and its my first car, i would recommend buying a sprinter with a 4ag already in it as i am currently putting a 4AG in mine and it has cost me a whole lot more than i first thought, but if you know what your doing and have access to a good workshop then you get to know a lot about the engine and car while you are doing the conversion.
as for drift, don't get too adventurous untill you have go the hang of it from track days etc.