If you just want to rescale them it sounds like you have a PC with a slicer or a slicer on a printer at least, which is fully capable of rescaling. In that case I can help you: Just print everything at 87,5% in the length direction (10,5/12), can't do anything for you in the Z direction nor width since I know nothing about your measurements. You might be 5´9" and have giant calves - I don't know . You might fall at the tail end of a normal distribution curve over lower leg lengths... You also might consider offering payment if you want someone to actually remodel the thing (not just scale) so that any joints and stuff aren't skewed and ruined by uneven rescaling if you are not just rescaling it evenly over all 3 axes. If you want the latter I'd say your best bet is to get in touch with the original modeler and supply them with all the necessary measurements for a proper tailored fit.