Both single spool and dual spool remote valves are available to fit your Ford tractor.
Used dual spool valves sometimes can be found in the Ads section of vintage tractor sites and ebay. The going rate for a complete, functinal dual spool valve is $400 - $500+.
New valves are still available from TISCO. The going rate for a complete dual spool kit (everything needed to install, including brackets, hoses, couplers, etc.) is around $1000.