Alan: 2 years ago I did the Ascent when I lived in Richmond BC - elevation 4' ASL - yep right at sea level. I knew altitude was going to be an issue as the local mountsins were all under 4000' - even whistler mountain tops out at just over 7100'.
To get used to the altitute I made a mini camp and went to Colorado/Manitou Springs for 4 days about 6 weeks before the race. I got in some runs on barr Trail eventually going to Barr Camp I also ground out a few Inclines and then did the GOG 10 Miler.
This mini camp let me know what I was in for and how my body would react. The first night in manitou I had a hard time sleeping and had a terrible headache. Once I learned to sip water through the night things got better.
Before the Ascent I arrived with my family on Tuesday - we did some touristy stuff and again I got in some training. This time we took the cog railroad to the top and I ran down and back up the last section of the Golden Stairs to get used to the terrain (I recommend a few boulder scrambles in your training). The next day we drove the road to the top and my wife let me out at Devils Playground and I ran the last 4 miles of the road to the top.
Altitude was a challenge and I found that above 12000' my HR kept dropping - I tried to pick up the pace but just couldn't.
Last year I did the same mini camp but this time I inluded a full ascent of PP (took the train down). Altitude wasn't an issue with no headache the first night. Regrettably I blew my hamstring 2 weeks before the race.
Short version of this is - go a few days early and get in a few runs at altitude. The psychological benefits of knowing what to do and what if feels like outweigh the physiological effects, if any.
See you on the start line- cheers and good luck.