I don't know what you want the finished size to be for your queen size bed? I always go to this site...
http://www.amishcountrylanes.com/Pages/QuiltSize.shtml
They have a great interactive calendar that allows you to add drop sizes, headboards, etc. Ex. for a queen 'coverlet' with the following specs this is what they recommend... 86" wide by 105" long -- 13" drop, 12" tuck [pillow tuck I imagine]. The original Jane finishes around 81-82" square. I would almost suggest simply increasing the sashing size somewhat. If you increase from 1/2" to 1" you would already end up with a 89" square. This way you wouldnt have to mess around with all of the measurements. You could further enlarge the quilt by enlarging the scallop width and possibly enlarging the final sashing around the central block section. Just a few suggestions. I know I wouldnt want to adjust everything!