I also am pretty sure it's a SIG Skyray-35. You can download the original instructions at
http://wanderings-ds.jimdo.com/sig-c-l-kits/
Just go down the page to kit CL25 - you'll find it there. Sorry 'bout the lack of a plan sheet. One day I'll find one, and it'll be included also. However, the kit IS still in production - you might call SIG and see if a copy of the instruction sheet can be bought.