You don't say whether you are planning on going solo or with a partner but your list of gear so far is a bit of overkill for either. Start some research by looking at the home page of this site and clicking on the 18 lb, 3 day pack. That is a good starting list for gear that will serve you for the entire JMT.

A zero degree bag would sure keep you warm but would be too heavy and too warm for what you would encounter. A 50 L pack is certainly large enough but can be heavy as well. The lightest tent is a lot heavier than any tarp. Water treatment chemicals are a lot lighter than a filter. Before you spend any money, do a lot more research and discover how to shave weight. You don't have to sacrifice much in the way of comfort to carry a light pack with complete safety. If you are at all handy with a sewing machine, you can save a lot of money.

I did the JMT last August; my gear load was about 15 lb including bear canister and a few comfort items. And, there are those who do it with even less. I also saw a lot of folks with packs that must have been 40 lb, not including food, struggling up some of the passes; some of them were bailing out. There is a lot of elevation to be gained and lost on the JMT; the lighter your pack, the easier it will be.

Doing the research is fun too!