The altima 3.5 motor is the VQ35 that is in the 350Z, good motor, not much potential for modding, but a good solid motor.
I 2nd the crown vic.
You ever think of an old 5.0? I believe the 93's(?) came stock with forged pistons. Very easy to mod, and make a decent low 13-high 12 sec car with all the bolt-ons and a nice bumbstick. If you do heads, youll gain a lot as well. Could be in the 300-330rwhp range when all said in done, which would allow for decent getup and go w/ your audio setup.
Ever think of an older Monte Carlo? Like 87 style. G-bodies are known for their menacing appearance. Easy to fit rims on, bags easy, and parts are super cheap for them. When I was working in my trunk, I could sit in it and still fit some more people in there, definately 2-3 dead bodies worth.
87 Monte Carlo SS...454 mmmmmmmmmmmmmmmmmmmmmmm