HPI is always a safe bet, their range is terrific. Try this, but I think a 1970 Boss 302 is not close enough to a '69 Shelby despite the basic Mustang being the same in both model years. There's a few from the mid-60s too, check out the panel on the right of the page. HTH
http://www.hpieurope.com/piw.php?lang=en&partNo=17546