This forum is really dead. I think I'm the only person who reads the Hardbody section, and I work 65 to 85 hours a week.
Your best bet for help is this online forum:
http://infamousnissan.com/forum/
I think it's about the most active forum for Nissan Hardbody trucks. Don't let the pictures of the low riders scare you off. Most members are normal truck owners.
The older trucks have a throttle body, and the fuel pressure regulator may be built into those units.
Nissan stops importing parts after 20 years, so every year parts get harder to find for our trucks.
If you can't find parts for the throttle body, a common work around is a Weber carb. I'm not sure what size, but I think it's the 42 Series.
My truck has multiport fuel injection, so I can't go that route. I wouldn't know how to trick all of the fuel injection sensors into working with a Weber carb.