a built d-series engine would be ok, imo a t3 on a non built 1.5/1.6 would be a waste. The single turbo 300zx from the late 80's was the t3, im not sure of the exact trim, but 5-6 psi would be undershooting the t3. A cheaper t25, t28, a hybrid t25/28, maybe even a hybrid t28/3 would be ok for such low boost levels. Build it up to handle at least 12 psi, then turbo it with a t3. However, if you are a noob, dont turbo. Swap. Have somebody that did swaps before help you out. Theres a book by Corky Bell called Maximum Boost, you could learn alot about turbocharging from that book. Thats if your really, really, really, want to go turbo.

-brtecson