My approach has been to go for the 40ish miles average a week, but always trying to get close to the 10,000' up and down, though working on a hard week, then an easy week.
35 miles 8700'
60 miles 12500'
23 miles 8000'
60 miles 20,000'
I try and do two long days on the harder weeks, back to back as well. Several hours out over the two days. Practice not stopping and eating on the move.
On the easier running weeks I'll do 60+ hilly miles on the bike, maybe netting another 4-5K of ascent.
Oh, and I practice my downhill running technique. I've read many account in which a round's nemesis was in the descents due to weak quads.
Edit: I also like to make some runs as rough as possible under foot, avoiding footpaths, eg tussocks, rocks, heather, bracken.