I was wondering the actual distance of the front straight at Lime Rock, from the bottom of the downhill to turn 1?

Basically, I am trying to figure out if I will run out of revs by changing the gearing in my diff. I am only pulling 6400 in 4th when I reach turn one

As an English major in college, I am open to any quick conversion calculators out there on the web, or the formula that I should use to determine the distance covered, while accelerating in a particular gear. I know wheel circumference, car weight, tranny gear ratio, diff ratio, and approximately how fast i am going at the bottom of the downhill. Am I missing any values?

I am going to post this in "Tech Talk" as well.

Thanks.

Dave