As has been said, you dont need lots of power in a Z, for such a cheap, reliable, easy to get power from and relatively easy conversion, go an RB20DET. There is a bloke in Canberra with a 240Z RB20DET and it goes really well with very few mods and still flogs a lot of other cars on the road. I would be spending the money on suspension if I were you, no point in having balls loads of torque and power when you will struggle to get it down.