what turbo you get depends a lot on the manifold. let me put it to you this way: if there is a premade (or one for sale) with a t series flange (where the turbo attaches to the manifold) it would be easier to get a t series turbo. if you get a flange/manifold for a g series, get a g. t's are bigger than g's, so your power will come later in your rev band. id suggest for simplicity that you check out a 14g (stock on dsm's btw). theyre plentiful, and are usually good for around 20lbs max. they ran at 9 stock (if i remember right). dont go bigger than a 14g. even the t3 might be too big unless you can up the boost safely. if youre serious about buying a turbo and manifold, i can hook you up. my dsm buddy has lots of stock stuff (injectors, manifolds, turbos, etc). let me know on, say, saturday or so when im back at home and ill see what he has.
EDIT: size conversions
14g is smaller than a t3, but is close. good up to 20lbs
16g is smaller than a t3/t4, but close. good for around 35lbs.
20g is *tiny* compared to a t4. good for about 50lbs.