Back to the OP - no way of knowing what you can get to re FTP as it depends on stuff like your VO2 max and, essentially, your genetic fortune.
Based on people that I have ridden similar times to in events, I'd expect that some of the leading women doing TTs would have FTP in the region of 230-250. No way of knowing if you can get there until you try! But as others have said, you can do very well with less than that.
You certainly don't need anything like those numbers to perform ok in an ultra-race. To give you some actual figures, I was just looking at my data for the TCR before and I was down to 80-90W average power for the last few days and climbed Passo Giau at an average power of 130W (average cadence was 51, v. low gears). My weight then was about 70kg.
Your weight loss is impressive! It will help you on the flat as well as on hills as the smaller you are, the less frontal area you have to cause drag.
Lot's of good advice above but one thing that is not best advice is to train in a non-aero position. Power is quite position-specific so you need to train to develop xxx Watts not in the abstract, but in the position in which you want to do your riding on the road. Lots of coaches advise training on your racing bike for that reason.
Virtually everybody can produce more power in a sitting up position than an aero tuck, but they will end up riding slower as more drag. Much of the art of going fast is finding the right trade-off for you between higher power and lower drag.