There is always ebay. Or (I can't believe I'm doing this) SHO Shop sells a 63mm TB which is a bored out SVT TB. Direct bolt on. Summit has some 65mm and 70mm TB's in the Mustang section of the catalogue.

1998 Silver Frost SVT Contour born on...8/28/01[/i]
American Iron Shootout Radial Tire 2 Class Champion, Cecil County Dragway April 20, 2002