John, I'm a little late to this discussion, but here's my two cents.
First of all, great looking pizzas. If someone would have told me that those had come out of a gas deck oven, I wouldn't have believed them.
Now... regarding the mod. Just because you can hit 800+ with this oven doesn't necessarily mean that you should. I really have my doubts that this oven can survive very long running continuously at 825/850. Those kind of temps are hard on ovens. Neapolitan pizza is an incredibly noble goal, but I think, if you want to avoid having to buy a new oven, you should accept the fact that this oven can't really do Neapolitan bakes and instead do 4 minute NY bakes instead. That's really what these ovens were born to do. A 4 minute NY pie, made with typical NY malted bromated flour, will always be better than a 2+ minute caputo pizza, imo (as well as being far superior to 6-7 minute NY bakes). This transition should also be a heck of a lot more easier for your NY leaning customers. Many NY style lovers have a hard time making the transition to Neapolitan, so you'd be talking about a substantial advertising outlay to reach Neapolitan fans- and that's also assuming you're in an area that has enough Neapolitan lovers to support a Neapolitan pizzeria. In this forum, Neapolitan pizza probably has the market share, because it has a lot of obsessives, but in the real world, Neapolitan pizza is incredibly niche and generally requires urban markets with large populations to thrive.