I ordered mine for my '69 RI from Chandler pickguards (Pickguard Heaven) but they asked me to pencil trace the original and send it to them so they have the right pattern.
Very pleased with Chandler's work
P.S.: the pattern for a 69 RI was #10962, so for a 65 RI I guess it should be pattern #1096
since it the only other reissue pattern # left
(http://pickguards.us/pricemustang.html)