I rode them slightly higher than that, I reckon somewhere around .8ish. They are long sustained climbs and the gradients are not that extreme to point of pushing you into the red if you can control the urge to chase faster riders up the road. This is particularly important on the first two climbs of the Campologno and Pordoi.
Your starting grid is key as the further to the front the less you will be held up. 2015 was my first time and I started in the last pen, bit of a nightmare on Campologno as spent ages clipping in and out due to packed road.
I finished in 5’54 in 2015 and so secured a spot in the second grid. I got a spot again in 2018 and finished in 5,42 (170th overall) starting in the second grid.
My own strategy was ride around .80 IF on the climbs and recover on the descents. The only stop I made was on top of Giau for a drink/few gels. The Giau was horrendous and if you are racing the event its going to be a real battle of will keeping the pressure on the pedals. Falzerego was not the same level of torture as the Giau but if you are chasing a good time it will drain everything from you.
I hope to get back to the event in the next few years, greatest cycling experience I have ever had and still have ambitions of getting under the magical 5’20 but that might just be beyond me at 45 years young 
Here is my ride from 2018 but unfortunately didn’t have my power pedals.