I believe that if you want it to sound like it did originally you would need to use 42/43 gauge wire. However you might want to examine some of the DiMarzio patents which discuss winding a second coil with a thicker wire to produce a brighter sound more like a single coil. Lots of other good ideas in them, too.
Patent US5908998 - High inductance electromagnetic pickup for stringed musical instruments - Google Patents
This patent was used for their EJ Custom hb's and their Virtual P-90 and DLX-90 p'ups to get a brighter sound more like a single coil from a hb.
P.S. Here is a link for all of Steven Blucher's patents: