software estimation

I have a piece of code written to copy files, and a lot more, to a mainframe. I have to write another piece of code, from scratch, to do the same of actions to the same set to a UNIX box. I have to estimate how long it will take to write the second piece using the first piece as my starting block. Does anyone know of any methodologies which I can say, given x lines of code, it may take me n hours? The target language is PERL, but I could substitute C/C++ at a pinch.

Ah, google is my friend:

A good coder (and I am not) can write 20 LOC per hour, 500 (tested) LOC per person-week. I've just written 1500 LOC (probably more, including re-factoring) and it took me about 3 weeks. I originally estimated 10 days without doing any pseudo-code. So, not bad. Should have doubled it, though.