I would stick with a turbo that has compressor maps available, BW or Garrett. Your unlikely to find someone running a combo that will be similar, so trying to find a proven combination is not going to be GM LS easy.

Both BW and Garrett have programs, Match Bot , and they are very good. Make sure your data entered is accurate, and pay attention to where you are using the turbo in it's compressor map. I like the MatchBot because I can make changes to the formula to best make use of a combination.

I am running twin EFR 9180 turbo's with Tial 1.02 housings. Using MatchBot, this was the best compromise for staying in the efficient part of the compressor, spool time, and EMAP (back pressure in the manifold).