Damian, the single most important ingredient in Neapolitan pizza- the single most "puff" providing factor- is heat. If you can't break the 2 minute bake barrier- for both top and bottom, there's no amount of recipe tweaking or alterations to dough management that will help you.
You seem to be getting a good amount of top coloration in 3 minutes- thanks, I think, due to the slight droop of the broiler element, putting it very close to the pizza, but, for that broiler, with that many passes/wattage, without oven mods, 3 minutes is the best you're going to get.
The way I see it, you only have two options for working with this oven.
1. Mod the oven to a minimum of 750 deg. As you push the oven to a higher temp, there's definitely risks involved, and, I believe that the higher you go, the higher the risk, so 750+ is a pretty risky endeavor, but if you want Neapolitan pizza from this oven, I don't think you have a choice.
2. Accept your 3 minute fate and make great NY style pizzas. You might find one or two people that disagree, but I strongly believe that a 3 minute NY style pizza will always turn out better than a Neapolitan dough baked for 3 minutes. This means, as Gene suggested earlier, using a malted bread flour (along with a traditional NY style recipe).