...Here's what I know! I'am Looking at the '74L wireing Diagram.
You say the fuse 'Second from the Bottom', Blew.
That would be #11 at 15 amps and is suppose to handle only ONE fan motor(178F).
#12 fuse is 25 amps and carries the current for the second Fan(158F).
If only #11 Blew, and Both fans quit? Perhaps You have Both Fan Motors connected to a 15 amp fuse!? NO way would handle that High of Amperage!!
Also!! The Fuel gauge, AND ALL other gauges receive Current off the #12 fuse!!
#11 delivers to ONE radiator fan, Seatbelt warning System AND the BrakeLights!!
Be Careful!! You don't want to be driving around with NO Brakelights!
DoubleCheck and see if the #12 fuse has also Blown, take it out and TEST It!
I suspect that Your Gearshift into 4th and 'High Rev' may have caused enough of a 'Voltage Spike' to blow a already weakened 15 amp Fuse that was UNdervalue to begin with! I DO NOT believe the Ignition Switch to be the Problem! Because the #11 and #12 fuses are 'Ganged'(at the FuseBlock)and 'SHARE' Two(2)Incoming 12 Volt sources! And the 'Fuse Curcuit' shown above is UseLess!! Nothing is Identified! You must use the Wireing Diagram You will find in the Ford 'Technical Manual'!! Good-Luck with it!...