Why not dyno with the curent setup? Its hard to tell where you need gains without knowing where you are.
I am still learning as well but I have been researching the last few years due to general brokeassness. I do a lot of reading on nissan forums, evo forums, and miata forums since they have engines similar in displacement than ours. Honda forums has lots of info too, but their rev range is higher which skews choices a bit.
It is generally considered the 2876 is a turd because the compressor wheel is too big for the turbine. The turbine chokes before full potential of the 76 is realized and the extra mass of the bigger compressor makes the turbo lazy.
Similar story for the 3076 compared to the 71. If you really need the 76, step up to the GT35 frame. The gt3071 spools faster and has nearly the same output. Its just a better match.
The GT30 turbine is considered to be not as good as the GT28 and GT35. Most people go one way or the other.
Im only shooting for around 300 wheel with great drivability and response for track days. Gt2871 seems the best option. The Borg Warner EFR 6258 would be an even better choice if you can actually get your hands on one.