First, that turbo is really too small for your engine. It will work, but will become very restricted in the higher RPM range. The carb enclosure and blow through are the same thing BTW.....given that, I think I would go the blowthrough route.
The headers and pipe you have planned will work well. According to Corky Bell, 3.5 inch downpipe will support about 900 HP. You will be pushing to get 550 out of that turbo. I will just advise you do alot of reading and research and make sure you know what all is involved. If you have any questions, I can probably help. I have been there and done that.