welcome to the garage gordy, hope you're gonna send some pics to the editor for the gallery ... and you might want to check in at the
"Fire-bolt" forum - don't think yer off duty here

yes, 730 would indicate the 2nd color .... and I'd expect the combination's 2nd color would be put on a cab already painted completely with the 1st color, as they were ordered, and back then any govt truck would be ordered in their colors
Bill