Contemplating NaNo... 3 months early

It's going to be that time again soon enough. That time of year where everything else goes flying out the window in favour of spending an entire month doing nothing but write frantically to hit 50,000 words. Yep, soon indeed.

Okay, when I say "soon", I mean that in relative terms. I still have two and a half months before NaNo starts. (If you don't have the faintest idea what I'm talking about, look here.) Plenty of time, you'd think. However, I really want to do something for NaNo this year which is not yet another pull-an-idea-out-of-the-back-of-the-mental-closet kind of thing. Ideally, I'd like to either do the follow-up to the novel I wrote the year before last, or do a complete rewrite of the fantasy trilogy I started several years ago but never finished.

There are problems with both options. The first option with the follow-up novel will be difficult because before I can write the second half of the story, I need to rewrite the first half. It has a fair share of problems. While I am confident I can fix them, it's going to take time. Probably all of the next two and a half months, and that's if I don't spend a lot of time doing much of anything else. Doable, but difficult.

The second option, rewriting the first novel of the trilogy I began, is equally complicated. That trilogy began as a single story, intended to be one book. But as I expanded it, as I tried to dig deeper into the story to make it more meaningful, more interesting, more worthy of being written and read, it expanded enormously. It turned into a monster of a story that will take at least three books to tell, the way I've set it out. Now, keeping in mind that this was a few years ago, I now feel I overextended that a bit. I'm fairly confident I could cut it down, possibly to two novels, without losing the heart of the story. But doing this means not only recreating my main character (who, quite simply, is boring right now), but also ditching the 60k or so words I've done, as well as quite a lot of story planning. It means essentially taking all the world building and general plot ideas and rearranging it all into a more sensible and concise order. This also would likely take me the next two and a half months. Also doable but difficult.

So, to my writerly or readerly friends out there: any advice on how I decide which way to go with this one? I want to do both - but that quite simply won't happen. Ideally I'd like to make a choice by the end of the month, so I have time to do any prep work I need to do before November strikes!