Here's the situation in bulleted form:
a) I'm a 56 year old ex-racer (long ago) who's been back on the bike for ~1.5 years
b) I average ~140 miles per week in 5 days, most of it flat to rolling, some hills, all averaging ~ 18 - 20 mph 99% solo. Because I live in HOT AZ and have a long commute, I crowd most of the big rides in on the weekends
c) I want to ride the AZ hill climb championship on Mount Graham (20 miles, HC) and I'd like to do my best. Not looking to win, I just want to know that I left it all on the hill.
d) I have eight weeks to prepare
e) as of late, I've felt a bit stale, like I can't light the torch

I think I need to do some speed work. Lately I've been concentrating on getting longer, harder workouts in at the expense of my short, fast rides, so it feels like I don't have access to the higher gear. It feels like it's there...I can ride close to redline for a good long time, I am just having trouble getting it to shift up.
I really don't think it's over training, I'm very consious of that, I just think I'm in a rut.
My question is: How would you structure intervals over the next eight weeks? The race is NOT a crit, it'll be at least 1:45 long at a pretty constant pace, so explosive is not what I'm looking for. What I'm looking to do is to raise the red line. I have limited access to long hills. The only one close is about 5 miles long at around 4% grade average. I can drive to an HC (El Capitan) a couple of times too. Bike Ride Profile | 97miles near Superior | Times and Records | Strava
Anyone have any advice?