This tree has potential. I would reccomend help from a more experienced and trained individual. Lots of talented people in your area. Also in nearby Oregon. John at Bonsai Northwest. Matt Reel, Michael Hagedorn.
Essentialy the design will be based on where you can develop appropriate size branching to create a suitable foliage pattern to frame the trunk!
This foliage will need to be much less than the current amount, closer in with fewer lengthy boring sections of straight branches.
Also, it is important to understand the foliage characteristics of Sub Alpine Fir and plan a design that is compatible. Further shortening of the tree will make that difficult!
The natural tendency of foliage to curve upwards will make a cascade style challenging as well, requiring excessive wiring which sub alpine fir does not handle well.
Fortunately Sub Alpine Fir readily back buds and long branching can be reduced and compacted towards the interior over time.
Not trying to be negative, just hoping to aid in getting the most out of this material.
If the tree were to be mine at this point i would stop, begin root work and repot this spring, Grow out and cut back over the next few years to create new interior foliage, particularily in the top 2/3 of the tree. While developing the new foliage i would continue to work the roots and create the proper root ball for Bonsai purposes working towards a maintenance pot over the next three years. Both objective could be accomplished in that time and then i would begin styling. This would accomplish a more balanced choice of branches and foliage to pick from and a healthy tree with a solid root ball sited for Bonsai.