Its a 71 super course.

here's a pic


The fork that is on there is not original, its a steel replacement fork. I'd like to replace it (thats' right, replace the replacement) with a CrMo one that I've located. Specifically, this one http://www.universalcycles.com/shopp...&category=3617

I can order it in 3 lengths 150mm, 200mm and 250mm. I just want to know how to measure my existing fork so I know what length to order.


***EDIT***

to be more specific, the length I'm after is the Steerer Tube Length.