Yep, it can't hurt.
When i bought a new dizzy cap & rotor, the only place i could get them from was Nissan. No aftermarket mobs made them, so you may be stuck with going to Nissan.
I recommend that you replace the rotor at the same time.
A word of warning on aftermarket ignition leads:
I bought a brand new set Bosch leads and put them on the car. They had a little rubber seal on the bottom of the lead, which just fits down the spark plug hole (quite a firm fit) and over the top of the plug. After only a month or 2, i couldn't get the leads off. It turns out that these little rubber seals had caked themselves onto the edges of the spark plug holes and basically glued themselves in there. The result was that when the mechanics went to take the head off my car after the head gasket blew, the leads broke and ripped in half as they tried to remove them. They were stuck in that tight!
Luckily enough I took them back to where I bought them and the Bosch rep was kind enough to replace them for me, as it really was a shitty design on their part. So on the new leads, i immediately ripped off the rubber seals on the bottom (they were just glued on). Now the leads can't get stuck and i haven't had any drama's with them in the last 3 or 4 years, however long it has been....
Dan.