It looks like you have the pre-1970 water pump (and timing cover). If so, then there is no need for ultra compact fan clutch.
The notch in the fan blades helps provide additional clearance to the bubble top tanks (correct for a '68)
2706 3.3", 1.75"
2747 3.3", 1.62" (fan is closer to pulley)
2705 3.1", 1.53" (clutch shorter and fan closer to pulley)
