You can find this on the Sunn Catalog Thread at the top of this page. The Sceptre cab had 4-12" speakers in a staggered vertical arrangement. The cabinet measures 24" W. x 15" D. x 40" H. (add 2 inches to the height for castors). I have a 1968 example of this cabinet with the original, date-matched Jensens. The cabinet is hand dated on the interior 9-12-68.....my 14th birthday!
You can find tolex, corners and handles on eBay and other sources. 1st generation grille cloth is unobtanium. Conrad Sundholm has all the parts too; not sure about the 1st generation grille cloth, but I think he may have the 2nd style. Good Luck!