Hi, I used the Furman HM plan last year and had great results. I started on their 10k plan in the summer, and despite the lack of any runs over 10 miles, reduced my HM from 1:42 to 1:35, then followed the HM schedule and reduced that PB further to 1:31. I got down to 1:30:25 in the spring after a winter of just base training and I'm hoping having reintroduced some Furman sessions I'll be able to go sub-1:30 in the autumn.
Definitely base your training paces on the 5k time at least initially - these are all hard sessions and some of the intervals particularly can be impossible anyway without trying to go even faster! - but I found that as I got fitter I was able to adjust them down a bit when it seemed natural to do so.
As to whether you can realistically go sub-1:30 by February, it's hard to say - it depends on so many factors. Taking a further 8 minutes off your PB will be much harder than the 9 minutes you took off this year, but there's plenty of time so it's not out of the question. 6:52 may seem very fast to you now but then your current PB pace probably seemed very fast to you a year ago!
Good luck!
