90mpw is good.
16-18 mile long runs once every week or every other week is also good.
I think you can do more than just tempos "when you feel good" during base phase....you have to schedule them for 1-2 times per week.
Some workouts to consider:
40min "Tempo" run at marathon pace down to half marathon race pace
2 by 15-20min at LT "harder tempo" half marathon down to 10k race pace +5-10sec/mile
I think you should get the legs turning over also- some light fartlek or aerobic 400s,
12-20 by 400m @ 10k goal pace with 1:30 rec.
other days do strides, later in the base phase incorporate some "pre-vo2max work" (pre and in before not the runner).
8-10 by 1000m at current 10k pace with 1:30 rest.
mileage should go up and down...how you feel...push some highs:
example mileage totals per week:
80
90
85
105
80
95
etc.