Pulsar isnt an exact model, its just the name for the car, N15 Pulsars are just the japanese version of the N15 Almeras (Like the one in my picture).
If you have a 1.4 it's the GA14DE engine.
Imported pulsars can come with the GA15DE engine but it wasnt a UK option.
SRis etc have the GA16DE engine with 98hp. You'll need the complete engine. The wiring harness will just plug and play and the gearbox bolts up. I cant gaurantee it will run perfect without the 1.6 ECU, NATS ECU and keys (The keys have the immobiliser chip in that talks to the NATS ECU - Nissan Anti Theft System).
VZRs, GTis, Autechs etc all use the SR series engine which is a lot more different.