Check out the formulas here:
http://purplesagetradingpost.com/sumner/bvillecar/bville-spreadsheet-index.html#Horse%20Power%20NeededYou'll probably need to know your Cd and frontal area to get a good answer. Weight counts too, as although it sounds like you've got plenty of room, you run out of it PDQ.
I've done it, and I can tell you that it ain't as easy as it sounds! The DA could be as high as 7000' feet, so I think if you're running a newer car with EFI and an ECU, you'll have a better shot. When my kid and I made it (in a daily driver 350Z, with only a couple minor mods), there were a lot of pretty serious cars there that couldn't get the job done.
On one of my runs, I missed a shift (got 5th instead of 3rd!) and it cost me about 4 or 5MPH. So, there not much wiggle room.
The bottom line is that they don't call it the "Big, white dyno" for nothin'! Just show up and run to get your final answer.