Couple things:
You can send the injectors off to be tested/cleaned, which in light of circumstances would make sense. OTOH, if you have a friendly Ford dealer nearby you can typically source new Ford injectors for around $25ea. That's what I pay for 19# and 24# Ford Motorsport injectors in sets of eight. I'll bet the 8.1l actually uses one of those sizes, or something very close. But, even their 36# injectors are only $32, so not a big deal. Personally, I would be sorely tempted to have the injectors tested *anyway*, just to see if they could be the culprit. I don't deal well with unexplained failures.
I would personally not wrap your exhaust manifold. I know lots of people do it and don't have problems, but exhaust wraps don't last forever and I imagine replacing would be a pain. Exhaust wraps can cause manifold cracking under certain excessive heat circumstances, which is also rare but also a pain! Finally, they trap moisture and can lead to rust (not to mentioned premature wrap failure), which also would be a pain. If you'd like to reduce heat, I'd strongly encourage pulling the manifolds and sending them to Swain or Jethot et al for ceramic coating. It's typically about $150 per part and you get a coating that lasts pretty much forever. Additionally, the coating is applied *inside* the manifold, so unlike exhaust wrap the heat stays inside the manifold, rather than trapped inside the wrap, cooking the metal. On an installed engine, wrap is a convenience and there are pros and cons to weigh, but if the engine is out and manifolds off, there is zero reason not to coat them if you're looking for some thermal management.
I don't know much about the V10 electronics, but on a 2004 I would expect only one temp sensor for both the gauge and the ECM, so what you're seeing on the gauge is probably what the ECM is seeing. A Scanguage puts numbers to it, but 5 or 10 degrees variance just isn't going to make a difference... not the point you cause engine damage, anyway. It would be very quick to tell how close they are with a one-time read on an OBDII tool. All that isn't to say I wouldn't buy a Scangauge - they're super handy to be sure - just there may be other approaches too.
If you're interested in a Scangauge, I'd personally recommend taking a hard look at the Ultragauge. I think it's an equal product and quite a bit cheaper. I use one in my Jag as the factory gauge only has three positions - cold, not cold, and too late. Rather annoying, especially when the cooling fan relay fails.
On the subject, once the motor is back in, you might want to monitor fuel pressure for a while. I'm not sure if the 2004 V10 has a fuel pressure sensor like most newer cars do, but I'd really suspect a fueling issue as the source of the failure. It's certainly possible low pressure just killed #2 first, randomly. I'd definitely want to keep my eye on that. You could of course use a mechanical gauge off the test port, but that's rather inconvenient. Installing a digital sensor while everything is apart would seem like a good investment to me.
