Definately put a decent converter in it. My take on having had a 2,800 high STR converter in my Express van that I tow with for the past 3 years is all positive. My fuel mileage actually improved around town and stayed the same on the highway. When you are sitting in gear the engine has less load on it and the van has almost no tendency to creep forward when you take your foot off the brake. The higher str and stall speed also keep the engine from seeing as much load starting off from a stop which means it gets rolling more easily with less throttle. Once rolling I am in 2nd gear by 10-15 mph under very light throttle and the converter locks almost immediately after the 1-2 shift and stays locked all the way through the gears. If I am heavier on the throttle it holds the gears out progressively longer and locks up later. If I go WOT it locks the converter at about 4,000 rpm in 2nd gear and unlocks right before the upshift and relocks again after the 2-3 shift. This is not 1980 any longer. A decent converter drives like the stock converter until you put your foot into it. With the 4L80E or in my case 85E you can lock the converter in all gears except 1st or Reverse.
As far as injectors go. The stock gen 3 6.0L engines are running the injectors near maxed out on stock engines. In my experience even putting a cold air intake, headers and exhaust will max them out, much less a cam. L59 5.3 flex fuel injectors or 8.1 HO Marine injectors are both logical upgrades and necessary for a cam. The cammed 6.0L I have in the 87 G20 van has the 42 lb/hr 8.1 HO marine injectors and actually comes fairly close to maxing out themself. See about 87% duty cycle at 6,500 rpm.
My Pro4x Nissan Titan also had a converter that stalled about 2,500 rpm from the factory. Never felt it an issue at all off-road. In 4 wheel drive low it would pull the truck forward at 1,000-1,500 rpm with ease.
If I were building it the truck would have an Elgin E-1840P aka Sloppy Stage 2 cam and a 2,800 high str converter with a triple disc lockup clutch. That cam is easy to tune and easy on valve train parts as well as works well with or without forced induction.
I will also say a couple of years ago a friend of mine and I went through the LQ4 in his massive cutaway van with the tool box rear loaded down with a/c tools and parts that serves for his business. He does a/c contractor work and pulls a good size trailer. His LQ4 had dropped a valve sear. We sent the short block out for a stock rebuild, put bone stock 862 5.3 heads, with the springs changed and the E-1840P. Put a stock 4.3 converter in the 80E. Added a set of shorty headers and left the factory 3" dual piping off the manifolds. That 6.0L pulled like a freight train. The 4.3 converter stalls about 2,400 rpm behind a 6.0L and has a double stator that gives it a higher str.
