IMO the best thing to do is go to a local cruise in a few times, meet the guys there and maybe one of them wont mind you getting the demensions off of their car. Reason I say this is because that way if you screw up with the numbers then it's your fault rather then someone else give you the wrong demensions. Find out all the demensions you need to know and then go to their home or something and get it all. That way too you will get to do it yourself, look the car over and possibly get more idea's instead of just from a picture.
Good luck!