I remembered wrong (of course!
) and now I am at home and looked it up it was the other way around.
340lbs of drag and 370lbs of lift at the front end are the figures they estimate(?) at 100mph. So drag is not quite so bad as I thought.
I always figured it would be hard to push a 1970 Challenger over 165-170mph which is why I said I would put money on you not going more than 180mph no matter how much power you had. I think you would start getting bits collapsing or ripping off with the pressures if nothing else.
I can tell you everything seems OK at 145mph though.