here´s a direct link to the Joe´s page
http://www.go143.de./index.php?id=229it´s german, but you can see the main measurement.
As a starting point, artin chassis could be the better choice, as it is easy to lengthen and to convert to a svivel guide.
if you want to go with a go! chassis, there seem to be enough cars that will fit with the wheel base you specified, but most of them will be wider than what you need.
If want to have pics of lenghtened artin chassis, let me know.
Peter