So, if I understand correctly, you’ve imported a jpg sequence into FCP and are just trying to render it in the timeline, which is giving you a 2-day estimate. Is this right?
I used to use a lot of 1080 png sequences in FCP, and this is what I did. Let me know if it works for you. First use Quicktime Pro (Version 7, which gets hidden in the Utilities folder in Applications when you upgrade to Snow Leopard) to “Open image sequence” and select the first image in the sequence. Save this as a reference movie. Then import that into FCP and see how it works. Also, be warned that if you change any of the files in that image sequence, you will have to recreate the reference movie or Final Cut will give you a “General Error” when you try to render it.