I lived in the Grande Prairie area for 11 years from 1980 to 1991. At that time, Hwy 40 was completely gravel, extremely remote, and usually travelled by large trucks which threw rocks everywhere in their wake. You could always tell the people in the Grande Prairie area who had used Hwy 40 to get to or from Jasper ... they were the ones with the cracked windshields!
I believe some paving has been done, but I haven't been on it since sometime in the late 1980s so I couldn't say for sure how much has been paved or what sort of condition it is in.
You might consider heading west to Hwy 43 and heading up it. It is paved all the way and was in pretty decent condition in the early 1990s. If I'm not mistaken they were twinning it to Whitecourt last summer. Going that way you would also encounter more civilization ... more opportunities for acquiring supplies etc.