Dan;
Effective training for mountain races with lots of vert needs to include a lot of vert. The demands of running/hiking up hill on variable gradients are quite different than those of flat running. I’d recommend using the guidelines in our book Training for the Uphill Athlete to design an effective plan to be sure you are including enough vert. The one thing you will not get on the machines is the specific strength building that cones from down hill running. If you can get in on day a week on actual stairs where you hike/run up and run down your quads will thank you on race day.
Scott