I have a '68 C-10 with a 250 and a set of Hedman headers. The headers are nice, but like you said, they hang below the frame. If you need a measurement I can try and get you one in a few days. John

'68 C-10 - 250 with Edelbrock 600cfm 4 barrel, Offy intake, Hedman headers and true duals, HEI, MSD 6A box, relocated gas tank
Soon to have: T-5 tranny