Present model calibration results in methods section or results section?
IMHO It doesn't belong in your main results section, as it isn't the results of your study - simply an intermediate step similar to testing the correct functioning of a bit of lab equipment. Nevertheless, it may be a substantial achievement in its own right. 

If you must stick to "method" and "results" sections, I'd add a "model validation" subsection to the Method one. You may want to refer to it in your conclusions as though it were a result, to highlight how trustworthy you believe the model to be.