Why such a big turbo?
Go check ray hall turbocharging its austrailian site has great app on it I ran up to a 5.0 liter, twins with intercooler. GT2871r fix bill very well from 289cubs up to 302 .64ar versions heck I could even run the same turbo in low boost form on my 454.
Figure 66 lb air flow, heck even a 5.3 probably won't need more than 68lb.still well within the GT2871R and up the hot side to .84 version to ease back pressure.