As for the accessories, there isn't a lot of difference. The power steering pump is any of the Frontier/Xterras that has the 3.3. for all I know, the 3.0 might even work with just a pulley swap. I originally had a Quest alternator on my 3.0, but I had to swap the pulley and shim it if I recall correctly and fab a new tensioner bracket to make it fit the 3.0. I wound up using the original pulley and the Frontier brackets when I changed to the 3.3. the alternator from an early to mid 90's Quest is what I used. Mercury Villager is the same critter, just picked from what I found in my local salvage yard.
With the cams, hard to say. Only reason to swap the is the 3.3 cams are slightly milder. They won't make a huge difference, the 3.3 I have is running the stock ones.
Nissan upgraded the injector plugs with the 3.3, and got rid of the annoying Bosch style clips. I think I just unwrapped the sub harnesses of my old engine and new one. Then I pulled the pins from the plugs that connect to the main and swapped the plugs. Then I rewrapped the harness. I believe I switched out the distributor and coil wires and plugs since the distributors are different. The 3.3 has the coil internal to the distributor while the 3.0 is external.
If I could figure out how to post photos, I can take some pictures of my setup and share. When the hood is open, only an old Nissan guy can tell that the engine is different. The right valve cover has the extended filler neck, the belts are flat, and the oil filter is moved from the right side to the front. Other than that, it looks like any other VG30. Even says so on the intake plenum.
I think the hardest part is to physically remove and install the engine in the truck. The space is tight and I believe you have to drop the front diff if you don't have a 3" body lift like I do. I have no regrets for that lift, it has made so many other things easier to do. #6 spark plug is not too bad anymore.