I cant pinpoint what is causing a tick in my engine ( ford 300 straight 6 1978 f-150)

A con rod sounds like youre hitting the engine with a hammer (knock), and that means a crank kit....crank shaft(machined down, under sized)cheaper, and rod and main bearings. A tick, push rod,lifter, or rocker arm, sounds like youre hitting the engine with a big screwdriver. Valve train noise (tick) is generally slower than crank noise because the cam turns at 1/2 crank speed.Stopping the spark will usually stop a knock If you short out each cylinder one at a time with a jumper wire to ground you can isolate the noise Dont do this if youre not mechanical the coil can kill you.......G'luck