I thoughts agree w/Bears63. The external control valve was going to be my last resort idea(plan B). The cores can be recored and it seems that the guy at heatercontrolvalve.com onlyworks on older Ranco control valves. He does nice work by the pics


http://s971.photobucket.com/albums/ae197/jon63c10
1963 c-10 shortbed stepside 427 BBC T16 HD 3 speed
1963 c-10 shortbed fleetside 348 "w" 1st gen big block & powerglide